Resist composition and method of forming resist pattern

ABSTRACT

A resist composition including a base component which exhibits changed solubility in a developing solution under action of acid and an acid generator which generates acid upon exposure, the base component containing a polymeric compound containing a structural unit represented by general formula (a0-1) and the acid generator containing a compound represented by general formula (b1). In the formulae, R represents H, an alkyl group of C 1 to 5  or a halogenated alkyl group of C 1 to 5 ; Ya 1  represents a single bond or a divalent linking group; La 1  and La 2  represents —SO 2 — or —C(═O)—; Ra 1  represents a cyclic group which may have a substituent and the like; n 1  and n 2  represents 0 or 1; R 11  represents a cyclic group of C 5 to 30  which may have a substituent; V 11  represents a single bond or an alkylene group of C 1 to 6 ; L 11  represents an ester bond; Y 11  represents an alkylene group of C 1 to 5  which may have a fluorine atom; m represents an integer of 1 or more; and M m+  represents an organic cation having a valency of m.

Priority is claimed on Japanese Patent Application No. 2013-094729,filed on Apr. 26, 2013 and Japanese Patent Application No. 2014-067153,filed on Mar. 27, 2014, the content of which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a resist composition and a method offorming a resist pattern.

BACKGROUND ART

In lithography techniques, for example, a resist film composed of aresist material is formed on a substrate, and the resist film issubjected to selective exposure of radial rays such as light or electronbeam through a mask having a predetermined pattern, followed bydevelopment, thereby forming a resist pattern having a predeterminedshape on the resist film.

A resist material in which the exposed portions become soluble in adeveloping solution is called a positive-type, and a resist material inwhich the exposed portions become insoluble in a developing solution iscalled a negative-type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization.

Typically, these miniaturization techniques involve shortening thewavelength (increasing the energy) of the exposure light source.Conventionally, ultraviolet radiation typified by g-line and i-lineradiation has been used, but nowadays KrF excimer lasers and ArF excimerlasers are starting to be introduced in mass production of thesemiconductor elements. Furthermore, research is also being conductedinto lithography techniques that use an exposure light source having awavelength shorter (energy higher) than these excimer lasers, such aselectron beam, extreme ultraviolet radiation (EUV), and X ray.

Resist materials for use with these types of exposure light sourcesrequire lithography properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified resist composition is used, which includes a base materialcomponent that exhibits a changed solubility in a developing solutionunder the action of acid and an acid generator component that generatesacid upon exposure. For example, in the case where the developingsolution is an alkali developing solution (alkali developing process), achemically amplified positive resist which contains, as a base component(base resin), a resin which exhibits increased solubility in an alkalideveloping solution under action of acid, and an acid generator istypically used. If the resist film formed using the resist compositionis selectively exposed during formation of a resist pattern, then withinthe exposed portions, acid is generated from the acid generatorcomponent, and the action of this acid causes an increase in thepolarity of the base resin, making the exposed portions soluble in thealkali developing solution. Thus, by conducting alkali developing, theunexposed portions remain to form a positive resist pattern. On theother hand, in the case where such a resist composition is applied to asolvent developing process using a developing solution containing anorganic solvent (organic developing solution), the polarity of the baseresin at exposed portions is increased, whereas the solubility atexposed portions in an organic developing solution is relativelydecreased. As a result, the unexposed portions of the resist film aredissolved and removed by the organic developing solution, and a negativeresist pattern in which the exposed portions are remaining is formed.Such a solvent developing process for forming a negative-tone resistcomposition is sometimes referred to as “negative-tone developingprocess” (for example, see Patent Document 1).

Currently, resins that contain structural units derived from(meth)acrylate esters within the main chain (acrylic resins) are nowwidely used as base resins for resist compositions that use ArF excimerlaser lithography, as they exhibit excellent transparency in thevicinity of 193 nm (for example, see Patent Document 2).

Patent Documents 3 and 4 discloses a resist composition containing apolymeric compound which contains a structural unit having a divalentimide group or a divalent amide group on the side chain thereof. PatentDocument 5 discloses a resist composition containing a polymericcompound which contains a structural unit having a divalentsulfonylamide group on the side chain thereof.

DOCUMENTS OF RELATED ART Patent Document

-   [Patent Document 1] Japanese Unexamined Patent Application, First    Publication No. 2009-025723-   [Patent Document 2] Japanese Unexamined Patent Application, First    Publication No. 2003-241385-   [Patent Document 3] Japanese Unexamined Patent Application, First    Publication No. 2006-63318-   [Patent Document 4] WO2012/043102-   [Patent Document 5] Japanese Unexamined Patent Application, First    Publication No. 2012-203261

SUMMARY OF THE INVENTION

As further progress is made in lithography techniques andminiaturization of resist patterns, further improvement in resistmaterials has been demanded in terms of various lithography properties.

However, in the resist compositions disclosed in Patent Documents 3 to5, further improvement in roughness of the resist pattern is required.

The present invention takes the above circumstances into consideration,with an object of providing a resist composition which exhibitsexcellent lithography properties, and a method of forming a resistpattern using the resist composition.

A first aspect of the present invention is a resist compositionincluding a base component (A) which exhibits changed solubility in adeveloping solution under action of acid and an acid generator component(B) which generates acid upon exposure, the base component (A)containing a polymeric compound (A1) having a structural unit (a0)represented by general formula (a0-1) shown below, and the acidgenerator component (B) containing a compound (B1) represented bygeneral formula (b1) shown below.

In the formula (a0-1), R represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Ya¹ represents a single bond or a divalent linking group; La¹ and La²each independently represents —SO₂— or —C(═O)—; Ra¹ represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent; n₁ and n₂ each independently represents 0 or 1, and atleast one of n₁ and n₂ is 1, provided that, when La¹ is —SO₂— and n₁ is1, n₂ is 1, and when La² is —SO₂— and n₂ is 1, Ya¹ is a chain-likedivalent linking group;

In the formula (b1), R¹¹ represents a cyclic group of 5 to 30 carbonatoms which may have a substituent; V¹¹ represents a single bond or analkylene group of 1 to 6 carbon atoms; L¹¹ represents an ester bond; Y¹¹represents an alkylene group of 1 to 5 carbon atoms which may have afluorine atom; m represents an integer of 1 or more; and M^(m+)represents an organic cation having a valency of m.

In the first aspect of the present invention, the polymeric compound(A1) preferably has a structural unit (a1) containing an aciddecomposable group that exhibits increased polarity by the action ofacid.

In the first aspect of the present invention, the polymeric compound(A1) preferably has a structural unit (a2) containing alactone-containing cyclic group.

A second aspect of the present invention is a method of forming a resistpattern, including: using a resist composition of the first aspect toform a resist film on a substrate; conducting exposure of the resistfilm; and developing the resist film to form a resist pattern.

The present invention takes the above circumstances into consideration,and according to the present invention, there are provided a resistcomposition which exhibits excellent lithography properties and a methodof forming a resist pattern using the resist composition.

MODE FOR CARRYING OUT THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

A “halogenated alkyl group” is a group in which part or all of thehydrogen atoms of an alkyl group is substituted with a halogen atom.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which part or all of the hydrogen atoms of an alkyl group or analkylene group have been substituted with fluorine atom(s).

The term “structural unit” refers to a monomer unit that contributes tothe formation of a polymeric compound (resin, polymer, copolymer).

A “structural unit derived from an acrylate ester” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of an acrylate ester.

An “acrylate ester” refers to a compound in which the terminal hydrogenatom of the carboxy group of acrylic acid (CH₂═CH—COOH) has beensubstituted with an organic group.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(α)) that substitutes the hydrogen atom bonded to the carbon atom onthe α-position is an atom other than hydrogen or a group, and examplesthereof include an alkyl group of 1 to 5 carbon atoms, a halogenatedalkyl group of 1 to 5 carbon atoms and a hydroxyalkyl group. A carbonatom on the α-position of an acrylate ester refers to the carbon atombonded to the carbonyl group, unless specified otherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”. Further,acrylate esters and α-substituted acrylate esters are collectivelyreferred to as “(α-substituted) acrylate ester”.

A “structural unit derived from hydroxystyrene or a hydroxystyrenederivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of hydroxystyrene or a hydroxystyrenederivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxy grouphas been substituted with an organic group and may have the hydrogenatom on the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent on the α-position of the aforementioned α-substitutedacrylate ester can be mentioned.

A “structural unit derived from vinylbenzoic acid or a vinylbenzoic acidderivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acidderivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof. Examples of thederivatives thereof include benzoic acid in which the hydrogen atom ofthe carboxy group has been substituted with an organic group and mayhave the hydrogen atom on the α-position substituted with a substituent;and benzoic acid which has a substituent other than a hydroxy group anda carboxy group bonded to the benzene ring and may have the hydrogenatom on the α-position substituted with a substituent. Here, theα-position (carbon atom on the α-position) refers to the carbon atomhaving the benzene ring bonded thereto, unless specified otherwise.

The term “styrene” includes styrene itself and compounds in which thehydrogen atom at the α-position of styrene has been substituted withanother substituent such as an alkyl group or a halogenated alkyl group.

A “structural unit derived from styrene or a styrene derivative” refersto a structural unit that is formed by the cleavage of the ethylenicdouble bond of styrene or a styrene derivative.

As the alkyl group as a substituent on the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent onthe α-position include groups in which part or all of the hydrogen atomsof the aforementioned “alkyl group as the substituent on the α-position”are substituted with halogen atoms. Examples of the halogen atom includea fluorine atom, a chlorine atom, a bromine atom and an iodine atom, anda fluorine atom is particularly desirable.

Specific examples of the hydroxyalkyl group as the substituent on theα-position include groups in which part or all of the hydrogen atoms ofthe aforementioned “alkyl group as the substituent on the α-position”are substituted with a hydroxy group. The number of hydroxy groupswithin the hydroxyalkyl group is preferably 1 to 5, and most preferably1.

The expression “may have a substituent” means that a case where ahydrogen atom (—H) is substituted with a monovalent group, or a casewhere a methylene (—CH₂—) group is substituted with a divalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

An “organic group” refers to a group containing a carbon atom, and mayinclude atoms other than carbon atoms (e.g., a hydrogen atom, an oxygenatom, a nitrogen atom, a sulfur atom, a halogen atom (such as a fluorineatom and a chlorine atom) and the like).

<<Resist Composition>>

The present invention of the present invention is a resist compositionincluding a base component (A) which exhibits changed solubility in adeveloping solution under action of acid and an acid generator component(B) which generates acid upon exposure, the base component (A)containing a polymeric compound (A1) having a structural unit (a0)represented by general formula (a0-1), and the acid generator component(B) containing a compound (B1) represented by general formula (b1).

The resist composition of the present invention includes a basecomponent (A) (hereafter, referred to as “component (A)”) which exhibitschanged solubility in a developing solution under action of acid, and anacid generator component (B) (hereafter, referred to as “component (B)”)which generates acid upon exposure. When a resist film is formed usingthe resist composition and the formed resist film is subjected to aselective exposure, acid is generated from the component (B) at exposedportions, and the generated acid acts on the component (A) to change thesolubility of the component (A) in a developing solution, whereas thesolubility of the component (A) in a developing solution is not changedat unexposed portions, thereby generating difference in solubility in adeveloping solution between exposed portions and unexposed portions.Therefore, by subjecting the resist film to development, the exposedportions are dissolved and removed to form a positive-tone resistpattern in the case of a positive resist, whereas the unexposed portionsare dissolved and removed to form a negative-tone resist pattern in thecase of a negative resist.

In the present specification, a resist composition which forms apositive resist pattern by dissolving and removing the exposed portionsis called a positive resist composition, and a resist composition whichforms a negative resist pattern by dissolving and removing the unexposedportions is called a negative resist composition.

The resist composition of the present invention may be either a positiveresist composition or a negative resist composition.

Further, in the formation of a resist pattern, the resist composition ofthe present invention can be applied to an alkali developing processusing an alkali developing solution in the developing treatment, or asolvent developing process using a developing solution containing anorganic solvent (organic developing solution) in the developingtreatment.

<Component (A)>

In the present invention, the term “base component” refers to an organiccompound capable of forming a film, and is preferably an organiccompound having a molecular weight of 500 or more. When the organiccompound has a molecular weight of 500 or more, the film-forming abilityis improved, and a resist pattern of nano level can be easily formed.

The organic compound used as the base component is broadly classifiedinto non-polymers and polymers.

In general, as a non-polymer, any of those which have a molecular weightin the range of 500 to less than 4,000 is used. Hereafter, a “lowmolecular weight compound” refers to a non-polymer having a molecularweight in the range of 500 to less than 4,000.

As a polymer, any of those which have a molecular weight of 1,000 ormore is generally used. Hereafter, a “resin” refers to a polymer havinga molecular weight of 1,000 or more.

As the molecular weight of the polymer, the weight average molecularweight in terms of the polystyrene equivalent value determined by gelpermeation chromatography (GPC) is used.

As the component (A), a resin, a low molecular weight compound, or acombination thereof may be used.

The component (A) may be a component that exhibits increased solubilityin a developing solution under action of acid or a component thatexhibits decreased solubility in a developing solution under action ofacid.

In the present invention, the component (A) may be a component thatgenerates acid upon exposure.

(Structural Unit (a0))

The resist composition of the present invention includes a polymericcompound (A1) containing a structural unit (a0) represented by generalformula (a0-1) shown below.

In the formula (a0-1), R represents a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Ya¹ represents a single bond or a divalent linking group; La¹ and La²each independently represents —SO₂— or —C(═O)—; Ra¹ represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent; n₁ and n₂ each independently represents 0 or 1, and atleast one of n₁ and n₂ is 1, provided that, when La¹ is —SO₂— and n₁ is1, n₂ is 1, and when La^(e) is —SO₂— and n₂ is 1, Ya¹ is a chain-likedivalent linking group.

In general formula (a0-1), R represents a hydrogen atom, an alkyl groupof 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbonatoms. The alkyl group of 1 to 5 carbon atoms is preferably a linear orbranched alkyl group of 1 to 5 carbon atoms, and specific examplesinclude a methyl group, an ethyl group, a propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a tert-butyl group, a pentylgroup, an isopentyl group, and a neopentyl group. The halogenated alkylgroup of 1 to 5 carbon atoms is a group in which part or all of thehydrogen atoms of the aforementioned alkyl group of 1 to 5 carbon atomshave been substituted with halogen atoms. Examples of the halogen atominclude a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a0-1), Ya¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Ya¹ is not particularly limited, andpreferable examples thereof include a divalent hydrocarbon group whichmay have a substituent and a divalent linking group containing a heteroatom.

(Divalent Hydrocarbon Group which May have a Substituent)

The hydrocarbon group as a divalent linking group may be either analiphatic hydrocarbon group or an aromatic hydrocarbon group.

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given. Specificexamples thereof include the same group as exemplified above for Va¹ informula (a1-1) described later.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

As examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof, a cyclic aliphatic hydrocarbon group which may have asubstituent containing a hetero atom in the ring structure thereof (agroup in which two hydrogen atoms have been removed from an aliphatichydrocarbon ring), a group in which the cyclic aliphatic hydrocarbongroup is bonded to the terminal of a linear or branched aliphatichydrocarbon group, and a group in which the cyclic aliphatic hydrocarbongroup is interposed within a linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

Specific examples of the cyclic aliphatic hydrocarbon group include thesame group as exemplified above for Va¹ in formula (a1-1) describedlater.

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

In the cyclic aliphatic hydrocarbon group, part of the carbon atomsconstituting the ring structure thereof may be substituted with asubstituent containing a hetero atom. The substituent containing ahetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—

Specific examples of the aromatic hydrocarbon group as a divalenthydrocarbon group include the same group as exemplified above for Va¹ informula (a1-1) described later.

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

(Divalent Linking Group Containing a Hetero Atom)

With respect to a divalent linking group containing a hetero atom, ahetero atom is an atom other than carbon and hydrogen, and examplesthereof include an oxygen atom, a nitrogen atom, a sulfur atom and ahalogen atom.

In the case where Ya¹ represents a divalent linking group containing ahetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —C(═O)—NH—Y²¹—, —NH—, and—NH—C(═NH)— (wherein H may be substituted with a substituent such as analkyl group or an acyl group), —S—, —S(═O)₂—, —S(═O)₂—O—, and a grouprepresented by general formula —Y²¹—O—Y²²⁻, —Y²¹—O—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²— [in theformulae, each of Y²¹ and Y²² independently represents a divalenthydrocarbon group which may have a substituent, O represents an oxygenatom, and m′ represents an integer of 0 to 3].

When the divalent linking group containing a hetero atom represents—C(═O)—NH—, —NH—, —NH—C(═NH)—, or —C(═O)—NH—Y²¹—, H may be substitutedwith a substituent such as an alkyl group, an acyl group or the like.The substituent (an alkyl group, an acyl group or the like) preferablyhas 1 to 10 carbon atoms, more preferably 1 to 8, and most preferably 1to 5.

In formula Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²—, Y²¹ and Y²² eachindependently represents a divalent hydrocarbon group which may have asubstituent. Examples of the divalent hydrocarbon group include the samegroups as those described above as the “divalent hydrocarbon group whichmay have a substituent” in the explanation of the aforementioneddivalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula—[Y²¹—C(═O)—O]_(m′)—Y²²—, m′represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and particularly preferably 1. Namely, it isparticularly desirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m′)—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

In the present invention, Ya¹ preferably represents an ester bond[—C(═O)—O-], an ether bond (—O—), a linear or branched alkylene group, acombination of these, or a single bond. When La² is —SO₂— and n₂ is 1,Ya¹ is a chain-like divalent linking group, and Ya¹ is preferably anester bond [—C(═O)—O-], an ether bond (—O—), a linear or branchedalkylene group or a combination of these.

In the formula (a0-1), La¹ and La² each independently represents —SO₂—or —C(═O)—, provided that, when La¹ is —SO₂— and n₁ is 1, n₂ is 1.

in the formula (a0-1), Ra¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and n₁ and n₂each independently 0 or 1, provided that at least one of n₁ and n₂ is 1.

As the cyclic group which may have a substituent, the chain-like alkylgroup which may have a substituent and the chain-like alkenyl groupwhich may have a substituent for Ra¹, the same cyclic group which mayhave a substituent, chain-like alkyl group which may have a substituentand chain-like alkenyl group which may have a substituent as those forR¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ in general formulae (b-1) to (b-3) described latercan be mentioned.

In the present invention, among these, as the cyclic group which mayhave a substituent for Ra¹, a monovalent alicyclic hydrocarbon group, anaryl group and an aralkyl group can be mentioned.

The monovalent alicyclic hydrocarbon group for Ra¹ preferably has 3 to20 carbon atoms and more preferably 3 to 12 carbon atoms, and may beeither monocyclic or polycyclic. As the monocyclic alicyclic hydrocarbongroup, a group in which one or more hydrogen atoms have been removedfrom a monocycloalkane is preferable. The monocycloalkane preferably has3 to 8 carbon atoms, and more preferably 3 to 6. Specific examples ofthe monocycloalkanes include cyclopropane, cyclobutane, cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycycloalkane preferably has 7to 20 carbon atoms, and more preferably has 7 to 12 carbon atoms.Examples of the polycycloalkane include adamantane, norbornane,isobornane, tricyclodecane and tetracyclododecane.

The aryl group for Ra¹ preferably has 6 to 18 carbon atoms and morepreferably 6 to 10 carbon atoms, and a phenyl group is particularlypreferable.

Examples of the aralkyl group for Ra¹ include a group in which analkylene group of 1 to 8 carbon atoms and the aforementioned “aryl groupfor Ra¹” are mutually bonded. An aralkyl group in which an alkylenegroup of 1 to 6 carbon atoms and the aforementioned “aryl group for Ra¹”are mutually bonded is preferable, and an aralkyl group in which analkylene group of 1 to 4 carbon atoms and the aforementioned “aryl groupfor Ra¹” are mutually bonded is particularly preferable.

The hydrocarbon group for Ra¹ is preferably a group in which part or allof the hydrogen atoms within a hydrocarbon group has been substitutedwith a fluorine atom, and more preferably a group in which 30 to 100% ofthe hydrogen atoms within a hydrocarbon group have been substituted withfluorine atoms. Among these, a perfluoroalkyl group in which all of thehydrogen atoms within the alkyl group has been substituted with fluorineatoms is particularly preferable.

The hydrocarbon group for Ra¹ may have a substituent. Examples of thesubstituents include an alkyl group of 1 to 5 carbon atoms, a halogenatom, an oxo group (═O), a hydroxy group (—OH), an amino group (—NH₂)and —SO₂—NH₂. In the hydrocarbon group, part of the carbon atomsconstituting the hydrocarbon group may be substituted with a substituentcontaining a hetero atom. The substituent containing a hetero atom ispreferably —O—, —NH—, —N═, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O.—

Examples of the hydrocarbon group for Ra¹ having a substituent includelactone-containing cyclic groups represented by general formulae(a2-r-1) to (a2-r-7) described later, —SO₂— containing cyclic groupsrepresented by formulae (a5-r-1) to (a5-r-4) described later, asubstituted aryl group represented by chemical formulae shown below, apolycyclic monovalent alicyclic hydrocarbon group which may have asubstituent, and a monovalent heterocycles represented by chemicalformulae shown below. The “*” in the formula represents a valence bond.

In the present invention, the chain-like alkyl group for Ra¹ which mayhave a substituent preferably has 1 to 8 carbon atoms, more preferably 1to 6, and still more preferably 1 to 4, and may be either linear orbranched. Specific examples include a methyl group, an ethyl group, apropyl group, a butyl group, a hexyl group and an octyl group.

Examples of the fluorinated alkyl group for Ra¹ include groups in whichpart or all of the hydrogen atoms within the alkyl group has beensubstituted with a fluorine atom. Specific examples includetrifluoromethyl group, —CH₂—CF₃, —CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃.

In the present invention, the structural unit (a0) is a structural unitrepresented by any one of general formulae (a0-1-1) to (a0-1-3) shownbelow.

In the formulae, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya¹represents a single bond or a divalent linking group; La¹ and La² eachindependently represents —SO₂— or —C(═O)—, provided that, when La² is—SO₂—, Ya¹ represents a chain-like divalent linking group; and n₁represents 0 or 1; Ra¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent.

In the formulae (a0-1-1) to (a0-1-3), R, Ya¹, La² and Ra¹ are the sameas defined above.

In the formula (a0-1-2), as the linking group for Ya¹, when La² is—C(═O)—, —C(═O)O-Va⁰¹- and —C(═O)NH-Va⁰¹- are preferable

Va⁰¹ is an alkylene group or a cyclic aliphatic hydrocarbon group. Amongthese, a (poly)cycloalkylene group is preferable.

When La² is —SO₂—, it is preferable that Ya¹ is preferably a singlebond, or —C(═O)O-Va⁰¹- (wherein Va⁰¹ is an alkylene group). When Ya¹ is—C(═O)O-Va⁰¹-, it is preferable to form —C(═O)O-Va⁰¹-La¹. When La² is—SO₂—, it is preferable that Ya¹ is a single bond, and La¹ is —C(═O)—(wherein n₁ is 1).

Specific examples of the structural unit (a0) are shown below. In theformulae, R is the same as defined above. In the formulae shown below,R^(α) represents a hydrogen atom, a methyl group or a trifluoromethylgroup.

As the structural unit (a0) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

The amount of the structural unit (a0) within the component (A1) basedon the combined total of all structural units constituting the component(A1) is preferably 1 to 50 mol %, more preferably 5 to 45 mol %, andstill more preferably 10 to 40 mol %.

When the amount of the structural unit (a0) is at least as large as thelower limit of the above-mentioned range, various lithography properties(such as sensitivity and LWR) can be improved. On the other hand, whenthe amount of the structural unit (a0) is no more than the upper limitof the above-mentioned range, a good balance can be achieved with theother structural units, and a resist pattern having excellent shape canbe obtained.

The resist composition of the present invention preferably includes astructural unit (a1), as well as the structural unit (a0).

(Structural Unit (a1))

The structural unit (a1) is a structural unit containing an aciddecomposable group that exhibits increased polarity by the action ofacid.

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof an acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereafter, referred to as“OH-containing polar group”) is preferable, a carboxy group or a hydroxygroup is more preferable, and a carboxy group is particularly desirable.

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

Here, the “acid dissociable group” is (i) a group in which the bondbetween the acid dissociable group and the adjacent atom is cleaved bythe action of acid; and (ii) a group in which one of the bonds iscleaved by the action of acid, and then a decarboxylation reactionoccurs, thereby cleaving the bond between the acid dissociable group andthe adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in adeveloping solution changes and, the solubility in an organic developingsolution is relatively decreased.

The acid dissociable group is not particularly limited, and any of thegroups that have been conventionally proposed as acid dissociable groupsfor the base resins of chemically amplified resists can be used.

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter,sometimes referred to as “acetal-type acid dissociable group”).

In the formula, Ra′¹ and Ra′² represents a hydrogen atom or an alkylgroup; and Ra′³ represents a hydrocarbon group, provided that Ra′³ maybe bonded to Ra′¹ or Ra′² to form a ring.

In the formula (a1-r-1), as the alkyl group for Ra′¹ and Ra′², the samealkyl groups as those described above for the alkyl groups as thesubstituent which may be bonded to the carbon atom on the α-position ofthe aforementioned α-substituted alkylester can be used, although amethyl group or ethyl group is preferable, and a methyl group isparticularly desirable.

As the hydrocarbon group for Ra′³, an alkyl group of 1 to 20 carbonatoms is preferable, an alkyl group of 1 to 10 carbon atoms is morepreferable, and a linear or branched alkyl group is still morepreferable. Specific examples thereof include a methyl group, an ethylgroup, a propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a tert-butyl group, a pentyl group, an isopentyl group, aneopentyl group, 1,1-dimethylethyl group, 1,1-diethylpropyl group,2,2-dimethypropyl group and 2,2-dimethybutyl group.

When Ra′³ is a cyclic hydrocarbon group, the hydrocarbon group may beeither an aliphatic group or an aromatic group, and may be either apolycyclic group or a monocyclic group. As the monocyclic alicyclichydrocarbon group, a group in which one hydrogen atom has been removedfrom a monocycloalkane is preferable. The monocycloalkane preferably has3 to 8 carbon atoms, and specific examples thereof include cyclopentane,cyclohexane and cyclooctane. As the polycyclic alicyclic hydrocarbongroup, a group in which one hydrogen atom has been removed from apolycycloalkane is preferable, and the polycycloalkane preferably has 7to 12 carbon atoms. Examples of the polycycloalkane include adamantane,norbornane, isobornane, tricyclodecane and tetracyclododecane.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup include aromatic hydrocarbon rings, such as benzene, biphenyl,fluorene, naphthalene, anthracene and phenanthrene; and aromatic heterorings in which part of the carbon atoms constituting the aforementionedaromatic hydrocarbon rings has been substituted with a hetero atom.Examples of the hetero atom within the aromatic hetero rings include anoxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich one hydrogen atom has been removed from the aforementionedaromatic hydrocarbon ring (aryl group); and a group in which onehydrogen atom of the aforementioned aryl group has been substituted withan alkylene group (an arylalkyl group such as a benzyl group, aphenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group or a 2-naphthylethyl group). The alkylene group(alkyl chain within the arylalkyl group) preferably has 1 to 4 carbonatoms, more preferably 1 or 2, and most preferably 1.

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below (hereafter, with respect to theacid dissociable group represented by the following formula (a1-r-2),the acid dissociable group constituted of alkyl groups is referred to as“tertiary ester-type acid dissociable group”).

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be mutually bonded to form aring.

As the hydrocarbon group for Ra′⁴ to Ra′⁶, the same groups as thosedescribed above for Ra′³ can be mentioned. Ra′⁴ is preferably an alkylgroup of 1 to 5 carbon atoms. In the case where Ra′⁵ and Ra′⁶ aremutually bonded to form a ring, a group represented by general formula(a1-r2-1) shown below can be mentioned.

On the other hand, in the case where Ra′⁴ to Ra′⁶ are not mutuallybonded and independently represent a hydrocarbon group, the grouprepresented by general formula (a1-r2-2) shown below can be mentioned.

In the formulae, Ra′¹⁰ represents an alkyl group of 1 to 10 carbonatoms; Ra′¹¹ is a group which forms an aliphatic cyclic group togetherwith a carbon atom having Ra′¹⁰ bonded thereto; and Ra′¹² to Ra′¹⁴ eachindependently represents a hydrocarbon group.

In the formula (a1-r2-1), as the alkyl group of 1 to 10 carbon atoms forRa′¹⁰, the same groups as described above for the linear or branchedalkyl group for Ra′³ in the formula (a1-r-1) are preferable. In theformula (a1-r2-1), as the aliphatic cyclic group which is formed byRa′¹¹, the same groups as those described above for the cyclichydrocarbon group for Ra′³ in the formula (a1-r-1) are preferable.

In the formula (a1-r2-2), it is preferable that Ra′¹² and Ra′¹⁴ eachindependently represents an alkyl group or 1 to 10 carbon atoms, and itis more preferable that the alkyl group is the same group as describedabove for the linear or branched alkyl group for Ra′³ in the formula(a1-r-1), it is still more preferable that the alkyl group is a linearalkyl group of 1 to 5 carbon atoms, and it is particularly preferablethat the alkyl group is a methyl group or an ethyl group.

In the formula (a1-r2-2), it is preferable that Ra′¹³ is the same groupas described above for the linear, branched or cyclic hydrocarbon groupfor Ra′³ in the formula (a1-r-1).

Among these, the same cyclic hydrocarbon group as those describe abovefor Ra′³ is more preferable.

Specific examples of the formula (a1-r2-1) are shown below. The “*” inthe formula represents a valence bond.

Specific examples of the formula (a1-r2-2) are shown below.

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, referred to as “tertiaryalkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each represents an alkyl group.

In the formula (a1-r-3), Ra′⁷ to Ra′⁹ is preferably an alkyl group of 1to 5 carbon atoms, and more preferably an alkyl group of 1 to 3 carbonatoms.

Further, the total number of carbon atoms within the alkyl group ispreferably 3 to 7, more preferably 3 to 5, and most preferably 3 or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent andcontains an acid decomposable group which exhibits increased polarity bythe action of acid; a structural unit derived from hydroxystyrene or ahydroxystyrene derivative in which at least a part of the hydrogen atomof the hydroxy group is protected with a substituent containing an aciddecomposable group; and a structural unit derived from vinylbenzoic acidor a vinylbenzoic acid derivative in which at least a part of thehydrogen atom within —C(═O)—OH is protected with a substituentcontaining an acid decomposable group.

As the structural unit (a1), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

As the structural unit (a1), structural units represented by generalformulae (a1-1) to (a1-3) shown below are preferable.

In the formulae, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Va¹represents a divalent hydrocarbon group which may contain an ether bond,an urethane bond or an amide bond; n_(a1) represents an integer of 0 to2;

Ra¹ represents an acid dissociable group represented by theaforementioned formulae (a1-r-1) or (a1-r-2).

Wa¹ represents a hydrocarbon group having a valency of n_(a2)+1; n_(a2)represents 1 to 3;

Ra² represents an acid dissociable group represented by theaforementioned formula (a1-r-1) or (a1-r-3).

Wa² represents a hydrocarbon group having a valency of n_(a3)+1; n_(a3)represents 1 to 3;

Va² represents a divalent hydrocarbon group which may contain an etherbond, an urethane bond or an amide bond; and

Ra³ represents an acid dissociable group represented by theaforementioned formulae (a1-r-1) or (a1-r-2).

In the aforementioned formula (a1-1), the hydrocarbon group for Va¹ maybe either an aliphatic hydrocarbon group or an aromatic hydrocarbongroup. An “aliphatic hydrocarbon group” refers to a hydrocarbon groupthat has no aromaticity. The aliphatic hydrocarbon group as the divalenthydrocarbon group for Va¹ may be either saturated or unsaturated. Ingeneral, the aliphatic hydrocarbon group is preferably saturated.

As specific examples of the aliphatic hydrocarbon group, a linear orbranched aliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Further, as the group for Va¹, a group in which the aforementioneddivalent hydrocarbon group has been bonded via an ether bond, urethanebond or amide bond can be mentioned.

The linear or branched aliphatic hydrocarbon group preferably has 1 to10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4,and most preferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable, and specific examples include a methylene group [—CH₂-], anethylene group [—(CH₂)₂-], a trimethylene group [—(CH₂)₃-], atetramethylene group [—(CH₂)₄-] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferable, and specific examples include alkylalkylene groups, e.g.,alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—,—C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylenegroups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—,—CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as—CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groupssuch as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl groupwithin the alkylalkylene group, a linear alkyl group of 1 to 5 carbonatoms is preferable.

As examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof, an alicyclic hydrocarbon group (a group in which twohydrogen atoms have been removed from an aliphatic hydrocarbon ring), agroup in which the alicyclic hydrocarbon group is bonded to the terminalof a linear or branched aliphatic hydrocarbon group, and a group inwhich the alicyclic hydrocarbon group is interposed within a linear orbranched aliphatic hydrocarbon group, can be given. As the linear orbranched aliphatic hydrocarbon group, the same groups as those describedabove can be used.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a monocyclic group or apolycyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic alicyclic hydrocarbon group, a group in which two hydrogenatoms have been removed from a polycycloalkane is preferable, and thepolycycloalkane preferably has 7 to 12 carbon atoms. Examples of thepolycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

The aromatic hydrocarbon group is a hydrocarbon group having an aromaticring.

The aromatic hydrocarbon group as the divalent hydrocarbon group for Va¹preferably has 3 to 30 carbon atoms, more preferably 5 to 30, still morepreferably 5 to 20, still more preferably 6 to 15, and most preferably 6to 10. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic cyclic group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup include aromatic hydrocarbon rings, such as benzene, biphenyl,fluorene, naphthalene, anthracene and phenanthrene; and aromatic heterorings in which part of the carbon atoms constituting the aforementionedaromatic hydrocarbon rings has been substituted with a hetero atom.Examples of the hetero atom within the aromatic hetero rings include anoxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring (arylene group); and a group in which onehydrogen atom has been removed from the aforementioned aromatichydrocarbon ring (aryl group) and one hydrogen atom has been substitutedwith an alkylene group (for example, a group in which one hydrogen atomhas been removed from an aryl group within an arylalkyl group such as abenzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group (alkyl chain within the arylalkyl group)preferably has 1 to 4 carbon atoms, more preferably 1 or 2, and mostpreferably 1.

In the aforementioned formula (a1-2), the hydrocarbon group for Wa¹having a valency of n_(a2)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic hydrocarbon grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof. As the specific examplesthereof, the same groups as those described above for Va¹ in theaforementioned formula (a1-1) can be mentioned.

The valency of n_(a2)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

In the aforementioned formula (a1-3), the hydrocarbon group for Wa²having a valency of n_(a3)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic hydrocarbon grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof. As the specific examplesthereof, the same groups as those described above for Va¹ in theaforementioned formula (a1-1) can be mentioned.

The valency of n_(a3)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

In the formula (a1-3), Va² is the same group as defined above for Va¹ inthe formula (a1-1).

As the structural unit represented by the aforementioned formula (a1-2),a structural unit represented by general formula (a1-2-01) shown belowis desirable.

In the formula (a1-2-01), Ra² represents an acid dissociable grouprepresented by the aforementioned formulae (a1-r-1) or (a1-r-3); n_(a2)is an integer of 1 to 3, preferably 1 or 2, and more preferably 1; c isan integer of 0 to 3, preferably 0 or 1, and more preferably 1; and R isthe same as defined above.

Specific examples of the structural units (a1-1) and (a1-2) are shownbelow. In the formulae shown below, R^(α) represents a hydrogen atom, amethyl group or a trifluoromethyl group.

In the component (A), the amount of the structural unit (a1) based onthe combined total of all structural units constituting the component(A) is preferably 20 to 80 mol %, more preferably 20 to 75 mol %, andstill more preferably 25 to 70 mol %. When the amount of the structuralunit (a1) is at least as large as the lower limit of the above-mentionedrange, various lithography properties such as sensitivity, resolutionand LWR are improved. On the other hand, when the amount of thestructural unit (a1) is no more than the upper limit of theabove-mentioned range, a good balance can be achieved with the otherstructural units.

The resist composition of the present invention preferably includes astructural unit (a2) described later, as well as the structural units(a0) and (a1).

(Structural Unit (a2))

The structural unit (a2) is a structural unit which contains alactone-containing cyclic group and which does not fall under thedefinition of the structural unit (a0).

When the component (A1) is used for forming a resist film, thelactone-containing cyclic group within the structural unit (a2) iseffective in improving the adhesion between the resist film and thesubstrate.

The aforementioned structural unit (a1) which contains alactone-containing cyclic group falls under the definition of thestructural unit (a2); however, such a structural unit is regarded as astructural unit (a1), and does not fall under the definition of thestructural unit (a2).

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya²¹represents a single bond or a divalent linking group; La²¹ represents—O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—; and R′ represents ahydrogen atom or a methyl group, provided that when La²¹ represents —O—,Ya²¹ does not represents —CO—; and Ra²¹ represents a lactone-containingcyclic group.

The divalent linking group for Ya²¹ is not particularly limited, andpreferable examples thereof include a divalent hydrocarbon group whichmay have a substituent and a divalent linking group containing a heteroatom.

(Divalent Hydrocarbon Group which May have a Substituent)

The hydrocarbon group as a divalent linking group may be either analiphatic hydrocarbon group or an aromatic hydrocarbon group.

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given. Specificexamples thereof include the same group as exemplified above for Va¹ inthe aforementioned formula (a1-1).

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

As examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof, a cyclic aliphatic hydrocarbon group which may have asubstituent containing a hetero atom in the ring structure thereof (agroup in which two hydrogen atoms have been removed from an aliphatichydrocarbon ring), a group in which the cyclic aliphatic hydrocarbongroup is bonded to the terminal of a linear or branched aliphatichydrocarbon group, and a group in which the cyclic aliphatic hydrocarbongroup is interposed within a linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

Specific examples of the cyclic aliphatic hydrocarbon group include thesame group as exemplified above for Va¹ in the aforementioned formula(a1-1).

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

In the cyclic aliphatic hydrocarbon group, part of the carbon atomsconstituting the ring structure thereof may be substituted with asubstituent containing a hetero atom. The substituent containing ahetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—

Specific examples of the aromatic hydrocarbon group as a divalenthydrocarbon group include the same group as exemplified above for Va¹ inthe aforementioned formula (a1-1).

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

(Divalent Linking Group Containing a Hetero Atom)

With respect to a divalent linking group containing a hetero atom, ahetero atom is an atom other than carbon and hydrogen, and examplesthereof include an oxygen atom, a nitrogen atom, a sulfur atom and ahalogen atom.

In the case where Ya²¹ represents a divalent linking group containing ahetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH— and —NH—C(═NH)—(wherein H may be substituted with a substituent such as an alkyl groupor an acyl group), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented bygeneral formula —Y²¹—O—Y²²—, —Y²¹—O—Y, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²— [in the formulae, each ofY²¹ and Y²² independently represents a divalent hydrocarbon group whichmay have a substituent, 0 represents an oxygen atom, and m′ representsan integer of 0 to 3].

When the divalent linking group containing a hetero atom represents—C(═O)—NH—, —NH—, or —NH—C(═NH)—, H may be substituted with asubstituent such as an alkyl group, an acyl group or the like. Thesubstituent (an alkyl group, an acyl group or the like) preferably has 1to 10 carbon atoms, more preferably 1 to 8, and most preferably 1 to 5.

In formula Y²¹—O—Y²², —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²—, Y²¹ and Y²² eachindependently represents a divalent hydrocarbon group which may have asubstituent. Examples of the divalent hydrocarbon group include the samegroups as those described above as the “divalent hydrocarbon group whichmay have a substituent” in the explanation of the aforementioneddivalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]_(m′)—Y²²—, m′represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and particularly preferably 1. Namely, it isparticularly desirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m′)—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

In the present invention, Ya²¹ preferably represents an ester bond[—C(═O)—O-], an ether bond (—O—), a linear or branched alkylene group, acombination of these, or a single bond.

In the formula (a2-1), Ra²¹ represents a lactone-containing cyclicgroup.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring) in thering skeleton thereof. The term “lactone ring” refers to a single ringcontaining a —O—C(═O)— structure, and this ring is counted as the firstring. A lactone-containing cyclic group in which the only ring structureis the lactone ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The lactone-containingcyclic group may be either a monocyclic group or a polycyclic group.

As the lactone-containing cyclic group, there is no particularlimitation, and an arbitrary group may be used.

Specific examples include groups represented by general formulae(a2-r-1) to (a2-r-7) shown below. Hereafter, “*” represents a valencebond.

In the formulae, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; n′ represents aninteger of 0 to 2; and m′ represents 0 or 1.

In general formulae (a2-r-1) to (a2-r-7), A″ represents an oxygen atom,a sulfonyl group or an alkylene group of 1 to 5 carbon atoms which maycontain an oxygen atom (—O—) or a sulfur atom (—S—). As the alkylenegroup of 1 to 5 carbon atoms for A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group. Examplesof alkylene groups that contain an oxygen atom or a sulfur atom includethe aforementioned alkylene groups in which —O— or —S— is bonded to theterminal of the alkylene group or present between the carbon atoms ofthe alkylene group. Specific examples of such alkylene groups include—O—CH₂—, —CH₂—O—CH₂—, —S—CH₂— and —CH₂—S—CH₂—. As A″, an alkylene groupof 1 to 5 carbon atoms or —O— is preferable, more preferably an alkylenegroup of 1 to 5 carbon atoms, and most preferably a methylene group. Asthe alkyl group, alkoxy group, halogen atom, halogenated alkyl group,halogenated alkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group forRa′²¹, the same alkyl groups, alkoxy groups, halogenated alkyl groups,—COOR″, —OC(═O)R″ and hydroxyalkyl groups as those described above asthe substituent which the divalent cyclic group for V₀ ^(a1) in thegeneral formula (a0) may have can be used.

Specific examples of the groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7) are shown below.

Among these, groups represented by the general formulae (a2-r-1) and(a2-r-2) are preferable, and groups represented by the general formulae(r-1c-1-1) to (r-1c-1-7) and (r-1c-2-1) to (r-1c-2-13) are morepreferable.

As the structural unit (a2) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a2), the amount ofthe structural unit (a2) based on the combined total of all structuralunits constituting the component (A1) is preferably 1 to 80 mol %, morepreferably 5 to 70 mol %, still more preferably 10 to 65 mol %, andparticularly preferably 10 to 60 mol %. When the amount of thestructural unit (a2) is at least as large as the lower limit of theabove-mentioned range, the effect of using the structural unit (a2) canbe satisfactorily achieved. On the other hand, when the amount of thestructural unit (a2) is no more than the upper limit of theabove-mentioned range, a good balance can be achieved with the otherstructural units, and various lithography properties such as DOF and CDUand pattern shape can be improved.

The resist composition of the present invention may also includestructural units (a3) to (a5), as well as the structural units (A), (a1)and (a2).

(Structural Unit (a3))

The structural unit (a3) is a structural unit containing a polargroup-containing aliphatic hydrocarbon group (provided that thestructural units that fall under the definition of structural units(a1), (a0) and (a2) are excluded).

When the component (A1) includes the structural unit (a3), it ispresumed that the hydrophilicity of the component (A1) is enhanced,thereby contributing to improvement in resolution.

Examples of the polar group include a hydroxyl group, a cyano group, acarboxyl group, or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and cyclic aliphatic hydrocarbon groups (cyclic groups). These cyclicgroups may be either monocyclic or polycyclic, and can be selectedappropriately from the multitude of groups that have been proposed forthe resins of resist compositions designed for use with ArF excimerlasers. The cyclic group is preferably a polycyclic group, morepreferably a polycyclic group of 7 to 30 carbon atoms.

Of the various possibilities, structural units derived from an acrylateester that includes an aliphatic polycyclic group that contains ahydroxyl group, a cyano group, a carboxyl group or a hydroxyalkyl groupin which part of the hydrogen atoms of the alkyl group have beensubstituted with fluorine atoms are particularly desirable. Examples ofthe polycyclic group include groups in which two or more hydrogen atomshave been removed from a bicycloalkane, tricycloalkane, tetracycloalkaneor the like. Specific examples include groups in which two or morehydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane. Of these polycyclic groups, a group in which two ormore hydrogen atoms have been removed from adamantane, a group in whichtwo or more hydrogen atoms have been removed from norbornane or a groupin which two or more hydrogen atoms have been removed fromtetracyclododecane are preferred industrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the hydrocarbon group within the polar group-containing aliphatichydrocarbon group is a linear or branched hydrocarbon group of 1 to 10carbon atoms, the structural unit (a3) is preferably a structural unitderived from a hydroxyethyl ester of acrylic acid. On the other hand,when the hydrocarbon group is a polycyclic group, structural unitsrepresented by formulae (a3-1), (a3-2) and (a3-3) shown below arepreferable.

In the formulae, R is as defined above; j is an integer of 1 to 3; k isan integer of 1 to 3; t′ is an integer of 1 to 3; l is an integer of 1to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.

j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbornyl group.

In formula (a3-3), t′ is preferably 1. l is preferably 1. s ispreferably 1. Further, it is preferable that a 2-norbonyl group or3-norbonyl group be bonded to the terminal of the carboxy group of theacrylic acid. The fluorinated alkyl alcohol is preferably bonded to the5th or 6th position of the norbornyl group.

As the structural unit (a3) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

The amount of the structural unit (a3) within the component (A1) basedon the combined total of all structural units constituting the component(A1) is preferably 5 to 50 mol %, more preferably 5 to 40 mol %, andstill more preferably 5 to 25 mol %.

When the amount of the structural unit (a3) is at least as large as thelower limit of the above-mentioned range, the effect of using thestructural unit (a3) can be satisfactorily achieved. On the other hand,when the amount of the structural unit (a3) is no more than the upperlimit of the above-mentioned range, a good balance can be achieved withthe other structural units.

In the present invention, the component (A1) may contain the structuralunit (a3). However, when the component (A1) doesn't contain thestructural unit (a3), sensitivity tends to be increased. Therefore, inthe present invention, the amount of the structural unit (a3) within thecomponent (A1) based on the combined total of all structural unitsconstituting the component (A1) is more preferably 0 mol %.

(Structural Unit (a4))

The structural unit (a4) is a structural unit containing an acidnon-dissociable cyclic group. When the component (A1) includes thestructural unit (a4), dry etching resistance of the resist pattern to beformed are improved. Further, the hydrophobicity of the component (A1)is further improved. Increase in the hydrophobicity contributes toimprovement in terms of resolution, shape of the resist pattern and thelike, particularly in an organic solvent developing process.

In the structural unit (a4), an “acid non-dissociable, aliphatic cyclicgroup” refers to a cyclic group which is not dissociated by the actionof the acid generated from the component (B) upon exposure, and remainsin the structural unit.

As the structural unit (a4), a structural unit which contains anon-acid-dissociable aliphatic cyclic group, and is also derived from anacrylate ester is preferable. Examples of this cyclic group include thesame groups as those described above in relation to the aforementionedstructural unit (a1), and any of the multitude of conventional groupsused within the resin component of resist compositions for ArF excimerlasers or KrF excimer lasers (and particularly for ArF excimer lasers)can be used.

In consideration of industrial availability and the like, at least onepolycyclic group selected from amongst a tricyclodecyl group, adamantylgroup, tetracyclododecyl group, isobornyl group, and norbornyl group isparticularly desirable. These polycyclic groups may be substituted witha linear or branched alkyl group of 1 to 5 carbon atoms.

Specific examples of the structural unit (a4) include units withstructures represented by general formulae (a4-1) to (a4-7) shown below.

In the formulae shown above, R^(α) represents a hydrogen atom, a methylgroup or a trifluoromethyl group.

As the structural unit (a4) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the structural unit (a4) is included in the component (A1), theamount of the structural unit (a4) based on the combined total of allthe structural units that constitute the component (A1) is preferablywithin the range from 1 to 30 mol %, and more preferably from 10 to 20mol %.

The structural unit (a5) is a structural unit represented by the generalformula (a2-1). In the formula (a2-1) Ra²¹ represents acarbonate-containing cyclic group or an —SO₂-containing cyclic group.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂— containingcyclic group may be either a monocyclic group or a polycyclic group.

As the —SO₂— containing cyclic group as a cyclic hydrocarbon group forRa²¹, a cyclic group containing —O—SO₂— within the ring skeletonthereof, i.e., a cyclic group containing a sultone ring in which —O—S—within the —O—SO₂— group forms part of the ring skeleton thereof isparticularly desirable. More specific examples of the —SO₂— containingcyclic group include groups represented by general formulae (a5-r-1) to(a5-r-4) shown below.

In the formulae, each Ra′⁵¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2.

In general formulae (a5-r-1) to (a5-r-4), A″ is the same as defined forA″ in general formulae (a2-r-1) to (a2-r-7). Examples of the alkylgroup, alkoxy group, halogen atom, halogenated alkyl group, —COOR″,—OC(═O)R″ and hydroxyalkyl group for Ra′⁵¹ include the same groups asthose described above in the explanation of Ra′²¹ in the generalformulae (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (a5-r-1) to (a5-r-4) are shown below. In the formulaeshown below, “Ac” represents an acetyl group.

As the —SO₂— containing cyclic group, a group represented by theaforementioned general formula (a5-r-1) is preferable, at least onemember selected from the group consisting of groups represented by theaforementioned chemical formulae (r-s1-1-1), (r-s1-1-18), (r-s1-3-1) and(r-s1-4-1) is more preferable, and a group represented by chemicalformula (r-s1-1-1) is most preferable.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring) inthe ring skeleton thereof. The term “carbonate ring” refers to a singlering containing a —O—C(═O)—O— structure, and this ring is counted as thefirst ring. A carbonate-containing cyclic group in which the only ringstructure is the carbonate ring is referred to as a monocyclic group,and groups containing other ring structures are described as polycyclicgroups regardless of the structure of the other rings. Thecarbonate-containing cyclic group may be either a monocyclic group or apolycyclic group.

The carbonate-containing cyclic group for Ra²¹ as a cyclic hydrocarbongroup is not particularly limited, and an arbitrary structural unit maybe used. Specific examples include groups represented by generalformulae (ax3-r-1) to (ax3-r-3) shown below.

In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom or an alkyl group; A″represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5carbon atoms which may contain an oxygen atom or a sulfur atom; p′represents an integer of 0 to 3; and q′ represents 0 or 1.

In general formulae (ax3-r-1) to (ax3-r-3), A″ is the same as definedfor A″ in general formula (a2-r-1).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxy alkyl group for Ra′^(x31)include the same groups as those exemplified for

Ra′²¹ in the formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (ax3-r-1) to (ax3-r-3) are shown below.

Among the examples shown above, an —SO₂— containing cyclic group ispreferable, a group represented by the general formula (a5-r-1) is morepreferable, and a group represented by any one of the chemical formulae(r-s1-1-1) and (r-s1-1-18) is still more preferable.

As the structural unit (a5) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a5), the amount ofthe structural unit (a5) based on the combined total of all structuralunits constituting the component (A1) is preferably 1 to 80 mol %, morepreferably 5 to 70 mol %, still more preferably 10 to 65 mol %, andparticularly preferably 10 to 60 mol %. When the amount of thestructural unit (a5) is at least as large as the lower limit of theabove-mentioned range, the effect of using the structural unit (a5) canbe satisfactorily achieved. On the other hand, when the amount of thestructural unit (a5) is no more than the upper limit of theabove-mentioned range, a good balance can be achieved with the otherstructural units, and various lithography properties such as DOF and CDUand pattern shape can be improved.

The component (A1) can be obtained, for example, by a conventionalradical polymerization or the like of the monomers corresponding witheach of the structural units, using a radical polymerization initiatorsuch as azobisisobutyronitrile (AIBN) or dimethyl2,2′-azobis(isobutyrate).

Furthermore, in the component (A1), by using a chain transfer agent suchas HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH, a —C(CF₃)₂—OH group can be introduced atthe terminals of the component (A1). Such a copolymer having introduceda hydroxyalkyl group in which some of the hydrogen atoms of the alkylgroup are substituted with fluorine atoms is effective in reducingdeveloping defects and LER (line edge roughness: unevenness of the sidewalls of a line pattern).

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (A1)is not particularly limited, but is preferably 1,000 to 50,000, morepreferably 1,500 to 30,000, and most preferably 2,000 to 20,000. Whenthe weight average molecular weight is no more than the upper limit ofthe above-mentioned range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theweight average molecular weight is at least as large as the lower limitof the above-mentioned range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

As the component (A1), one type may be used alone, or two or more typesmay be used in combination.

In the base component (A), the amount of the component (A1) based on thetotal weight of the component (A) is preferably 25% by weight or more,more preferably 50% by weight or more, still more preferably 75% byweight or more, and may be even 100% by weight. When the amount of thecomponent (A1) is 25% by weight or more, various lithography propertiesare improved.

In the resist composition of the present invention, as the component(A), one type may be used, or two or more types may be used incombination.

In the resist composition of the present invention, the amount of thecomponent (A) can be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Acid Generator Component; Component (B)>

The resist composition of the present invention contains an acidgenerator component (B) which generates acid upon exposure (hereafter,referred to as “component (B)”), and the acid generator component (B)includes a compound (B1) represented by general formula (b1) shown below(hereafter, sometimes referred to as “component (B1)”).

In the formula (b1), R¹¹ represents a cyclic group of 5 to 30 carbonatoms which may have a substituent; V¹¹ represents a single bond or analkylene group of 1 to 6 carbon atoms; L¹¹ represents an ester bond;represents an alkylene group of 1 to 5 carbon atoms which may have afluorine atom; m represents an integer of 1 or more; and M^(m+)represents an organic cation having a valency of m.

In the formula (b1), R¹¹ represents a cyclic group of 5 to 30 carbonatoms which may have a substituent.

The cyclic group is preferably a cyclic hydrocarbon group of 5 to 30carbon atoms, and the cyclic hydrocarbon group may be either an aromatichydrocarbon group or an aliphatic hydrocarbon group.

As the aromatic hydrocarbon group for R¹¹, groups in which one hydrogenatom has been removed from an aromatic hydrocarbon ring described abovein relation to the divalent aromatic hydrocarbon group for Va¹ in theformula (a1-1) or an aromatic compound containing two or more aromaticring can be mentioned, and a phenyl group or a naphthyl group ispreferable.

As the cyclic aliphatic hydrocarbon group for R¹¹, groups in which onehydrogen atom has been removed from a monocycloalkane or apolycycloalkane exemplified above in the explanation of the divalentaliphatic hydrocarbon group for Va¹ in the formula (a1-1) can bementioned, and a polycycloalkane is preferable. Among these, aspolycycloalkanes, polycycloalkanes containing a bridged ring-typepolycyclic skeleton such as an adamantyl group, a norbornyl group andthe like, and polycycloalkanes containing a condensed ring-typepolycyclic skeleton such as a cyclic group containing a steroid skeletoncan be mentioned. In the present specification, the term “steroidskeleton” means a skeleton (st) in which three 6-membered rings and one5-membered ring have been linked, and the structure thereof is shownbelow.

Further, the cyclic hydrocarbon group for R^(H) may contain a heteroatom like as a heterocycle, and specific examples thereof includelactone-containing cyclic groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7), —SO₂— containing cyclic groupsrepresented by the aforementioned formulae (a5-r-1) to (a5-r-4) andheterocycle groups represented by the aforementioned general formulae(r-hr-1) to (r-hr-16).

As the substituent for substituting the cyclic hydrocarbon group forR^(H), an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxyl group, an oxo group, a nitro group or the likecan be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to8 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group, a tert-butyl group or 1,5-dimethylhexyl group isdesirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom as the substituent include a fluorine atom,a chlorine atom, a bromine atom and an iodine atom, and a fluorine atomis preferable.

Example of the halogenated alkyl group as a substituent includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms such as a methyl group, an ethyl group, a propylgroup, an n-butyl group or a tert-butyl group have been substituted withthe aforementioned halogen atoms.

The cyclic group within R¹¹ preferably has 1 to 5 substituents. When R¹¹is a polycycloalkane containing a bridged ring-type polycyclic skeleton,R¹¹ preferably has 1 to 3 substituents. When the substituent is an alkylgroups, R¹¹ preferably has 2 to 3 substituents. When the substituent isa hydroxyl group or an oxo group, R¹¹ preferably has 1 substituent. WhenR¹¹ is a polycycloalkane containing a condensed ring-type polycyclicskeleton, R¹¹ preferably has 3 to 5 substituents. When the cyclic groupwithin R¹¹ has a substituent, LWR is further improved.

When the polycycloalkanes containing a condense ring-type polycyclicskeleton is a cyclic group containing a steroid skeleton, examplesthereof are shown below. The “*” in the formula represents a valencebond.

In the formula (b1), V¹¹ represents a single bond or an alkylene groupof 1 to 6 carbon atoms. Specific examples of the alkylene group for V¹¹include a methylene group [—CH₂-]; alkylmethylene groups suchas—CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂— and —C(CH₃)(CH₂CH₃)—,—C(CH₃)(CH₂CH₂CH₃)— and —C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂-];alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; and alkylpropylene groups such as—CH(CH₃)CH₂CH₂—.

In the present invention, V¹¹ is preferably a single bond or an alkylenegroup of 1 to 5 carbon atoms; when R¹¹ is the aforementioned aromatichydrocarbon group, a monocycloalkane, a polycycloalkane containing abridged ring-type polycyclic skeleton, or the aforementioned cyclichydrocarbon group containing a hetero atom, V¹¹ is more preferably asingle bond or a methylene group; and when R¹¹ is the aforementionedpolycycloalkane containing a condensed ring-type polycyclic skeleton,V¹¹ is more preferably a single bond or an alkylpropylene group.

In the formula (b1), L¹¹ represents an ester bond (—C(═O)O—, —O—C(═O)—).When L¹¹ is —C(═O)O— (that is, when the ester bond is arranged to formV¹¹—C(═O)O—Y¹¹), MEEF is improved.

Y¹¹ represents an alkylene group of 1 to 5 carbon atoms which may have afluorine atom.

In the present invention, as Y¹¹, a fluorinated alkylene group of 1 to 4carbon atoms is preferable, a fluorinated alkylene group of 1 to 2carbon atoms is more preferable, and —CF₂—, —CH₂CF₂—, and —CF₂CF₂— isstill more preferable.

Specific examples of the anion moiety of the compound represented byformula (b1) are shown below.

In the formula (b1), m is an integer of 1 or more; and M^(m+) is anorganic cation having a valency of m. Further, as examples of theorganic cation having a valency of m in the formula (hi), the samecations as those for M′^(m+) in general formulae (b-1) to (b-3)described later can also be given.

As the component (B), one type of these compounds may be used alone, ortwo or more types may be used in combination.

The amount of the component (B), relative to 100 parts by weight of thecomponent (A) is preferably from 0.5 to 60 parts by weight, morepreferably from 1 to 50 parts by weight, and still more preferably from1 to 40 parts by weight. When the amount of the component (B) is withinthe above-mentioned range, formation of a resist pattern can besatisfactorily performed. Further, by virtue of the above-mentionedrange, when each of the components are dissolved in an organic solvent,a uniform solution can be obtained and the storage stability becomessatisfactory.

The component (B) may include an acid generator component (B2) describelater, as well as the component (B1).

As the component (B2), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions can be used.

Examples of these acid generators are numerous, and include onium saltacid generators such as iodonium salts and sulfonium salts; oximesulfonate acid generators; diazomethane acid generators such as bisalkylor bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes;nitrobenzylsulfonate acid generators; iminosulfonate acid generators;and disulfone acid generators. Among these, onium salt acid generatorsare preferably used.

Examples of the onium salt acid generators include a compoundrepresented by general formula (b-1) shown below (hereafter, sometimesreferred to as “component (b-1)”), a compound represented by generalformula (b-2) shown below (hereafter, sometimes referred to as“component (b-2)”) and a compound represented by general formula (b-3)shown below (hereafter, sometimes referred to as “component (b-3)”).

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that, R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring; provided that, two of R¹⁰⁶ to R¹⁰⁷ may be mutuallybonded to form a ring; R¹⁰² represents a fluorine atom or a fluorinatedalkyl group of 1 to 5 carbon atoms; Y¹⁰¹ represents a single bond or adivalent linking group containing an oxygen atom; V¹⁰¹ to V¹⁰³ eachindependently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—; and M′^(m+) represents anorganic cation having a valency of m, provided that, the organic cationrepresented by the formula (b1) is excluded from the compoundrepresented by the formula (b-1).

{Anion Moiety}

Anion Moiety of Component (b-1)

In the formula (b-1), R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent.

(Cyclic Group which May have a Substituent)

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group.

As the aromatic hydrocarbon group, groups in which one hydrogen atom hasbeen removed from an aromatic hydrocarbon ring described above inrelation to the divalent aromatic hydrocarbon group for Va¹ in theformula (a1-1) or an aromatic compound containing two or more aromaticring can be mentioned, and a phenyl group or a naphthyl group ispreferable.

As the cyclic aliphatic hydrocarbon group, groups in which one hydrogenatom has been removed from a monocycloalkane or a polycycloalkaneexemplified above in the explanation of the divalent aliphatichydrocarbon group for Va¹ in the formula (a1-1) can be mentioned, and anadamantyl group or a norbornyl group is preferable.

Further, the cyclic hydrocarbon group may contain a hetero atom like asa heterocycle, and specific examples thereof include lactone-containingcyclic groups represented by the aforementioned general formulae(a2-r-1) to (a2-r-7), —SO₂— containing cyclic groups represented by theaforementioned formulae (a5-r-1) to (a5-r-4) and heterocycle groupsrepresented by the aforementioned general formulae (r-hr-1) to(r-hr-16).

As the substituent for substituting the cyclic hydrocarbon group, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxyl group, a carbonyl group, a nitro group or the like can beused.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom as the substituent include a fluorine atom,a chlorine atom, a bromine atom and an iodine atom, and a fluorine atomis preferable.

Example of the halogenated alkyl group as a substituent includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms such as a methyl group, an ethyl group, a propylgroup, an n-butyl group or a tert-butyl group have been substituted withthe aforementioned halogen atoms.

(Chain-Like Alkyl Group which May have a Substituent)

The chain-like alkyl group for R¹⁰¹ may be either linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15, and most preferably 1 to 10. Specific examplesinclude a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, an undecyl group, a dodecyl group, a tridecylgroup, an isotridecyl group, a tetradecyl group, a pentadecyl group, ahexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecylgroup, a nonadecyl group, an icosyl group, a henicosyl group and adocosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

(Chain-Like Alkenyl Group which May have a Substituent)

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and particularlypreferably 3 carbon atoms. Examples of linear alkenyl groups include avinyl group, a propenyl group (an allyl group) and a butynyl group.Examples of branched alkenyl groups include a 1-methylpropenyl group anda 2-methylpropenyl group.

Among the above-mentioned examples, as the chain-like alkenyl group, apropenyl group is particularly desirable.

As the substituent for substituting the chain-like alkyl group oralkenyl group for R¹⁰¹, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxyl group, a carbonyl group, a nitro group, an aminogroup, the same cyclic group as described above for R¹⁰¹ or the like canbe used.

Among these, in the present specification, as R¹⁰¹, a chain-like alkylgroup which may have a substituent or a chain-like alkenyl group whichmay have a substituent is preferable.

In the formula (b-1), Y¹⁰¹ represents a single bond or a divalentlinking group containing an oxygen atom.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, Y¹⁰¹ may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linkage groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amide bond (—C(═O)—NH—), a carbonyl group(—C(═O)—) and a carbonate group (—O—C(═O)—O—);

and a combination of any of the aforementioned non-hydrocarbon, oxygenatom-containing linking groups with an alkylene group. Furthermore, thecombinations may have a sulfonyl group (—SO₂—) bonded thereto. As thecombination, the linking groups represented by formulae (y-a1-1) to(y-a1-7) shown below can be mentioned.

In the formulae, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; and V′¹⁰² represents a divalent saturatedhydrocarbon group of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms.

As the alkylene group for V′¹⁰¹ and V′¹⁰², a linear alkylene group or abranched alkylene group can be used, and a linear alkylene group ispreferable.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂-]; alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂-]; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group)[—CH₂CH₂CH₂-]; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; a tetramethylenegroup [—CH₂CH₂CH₂CH₂-]; alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂— and —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylene group[—CH₂CH₂CH₂CH₂CH₂-].

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group described above for Ra′³ in theaforementioned formula (a1-r-1), and a cyclohexylene group,1,5-adamantylene group or 2,6-adamantylene group is more preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond oran ester bond, and linking groups represented by the aforementionedformulae (y-a1-1) to (y-a1-5) are preferable.

In the formula (b-1), V¹⁰¹ represents a single bond, an alkylene groupor a fluorinated alkylene group. The alkylene group or fluorinatedalkylene group for V¹⁰¹ preferably has 1 to 4 carbon atoms. As thefluorinated alkylene group for V¹⁰¹, a group in which part or all of thehydrogen atoms within the aforementioned alkylene group for V¹⁰¹ hasbeen substituted with fluorine atoms can be used. Among these, V¹⁰¹ ispreferably a single bond or a fluorinated alkylene group of 1 to 4carbon atoms.

In the formula (b-1), R¹⁰² represents a fluorine atom or a fluorinatedalkyl group of 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atomor a perfluoroalkyl group of 1 to 5 carbon atoms, and is more preferablya fluorine atom.

As specific examples of anion moieties of the formula (b-1),

when Y¹⁰¹ is a single bond, fluorinated alkylsulfonate anions such as atrifluoromethanesulfonate anion or a perfluorobutanesulfonate anion canbe mentioned; and when Y¹⁰¹ is a divalent linking group containing anoxygen atom, anions represented by formulae (an-1) to (an-3) shown belowcan be mentioned.

In the formulae, R″¹⁰¹ represents a chain-like alkyl group which mayhave a substituent, a chain-like alkenyl group which may have asubstituent, an aliphatic cyclic group which may have a substituent, agroup represented by any one of the aforementioned formulae (r-hr-1) to(r-hr-6), or a chain-like alkyl group which may have a substituent;R″¹⁰² represents a chain-like alkyl group which may have a substituent,a chain-like alkenyl group which may have a substituent, or an aliphaticcyclic group having 3 or 4 carbon atoms which may have a substituent;R″¹⁰³ represents an aromatic cyclic group which may have a substituent,an aliphatic cyclic group which may have a substituent, or a chain-likealkenyl group which may have a substituent; V″¹⁰¹ represents afluorinated alkylene group; L″¹⁰¹ represents —C(═O)— or —SO₂—, providedthat, when L″¹⁰¹ is —C(═O)—, n″ is 1; v″ each independently representsan integer of 0 to 3; q″ each independently represents an integer of 1to 20; and n″ represents 0 or 1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupdescribed above in the explanation of “cyclic group which may have asubstituent” are preferable. As the substituent, the same groups asthose described above for substituting the cyclic aliphatic hydrocarbongroup in the explanation of “cyclic group which may have a substituent”can be mentioned.

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group exemplified above as acyclic hydrocarbon group in the explanation of “cyclic group which mayhave a substituent” described above are preferable. As the substituent,the same groups as those described above for substituting the aromatichydrocarbon group in the explanation of “cyclic group which may have asubstituent” can be mentioned.

As the chain-like alkyl group for R″¹⁰¹ which may have a substituent,the same groups exemplified as the chain-like alkyl group for R¹⁰¹ arepreferable. As the chain-like alkenyl group for R″¹⁰³ which may have asubstituent, the same groups exemplified above as the chain-like alkenylgroup for R¹⁰¹ are preferable. V″¹⁰¹ is preferably a fluorinatedalkylene group of 1 to 3 carbon atoms, and particularly preferably—CF₂—, —CF₂CF₂—, —CHFCF₂—, —CF(CF₃)CF₂— or —CH(CF₃)CF₂—.

Anion Moiety of Component (b-2)

In formula (b-2), R¹⁰⁴ and R¹⁰⁵ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same groups as those defined above for “cyclicgroup which may have a substituent” in the aforementioned formula (b-1),provided that, R¹⁰⁴ and R¹⁰⁵ may be mutually bonded to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms,preferably 1 to 7, and more preferably 1 to 3. The smaller the number ofcarbon atoms of the chain-like alkyl group for R¹⁰⁴ and R¹⁰⁵ within theabove-mentioned range of the number of carbon atoms, the more thesolubility in a resist solvent is improved. Further, in the chain-likealkyl group for R¹⁰⁴ and R¹⁰⁵, it is preferable that the number ofhydrogen atoms substituted with fluorine atoms is as large as possiblebecause the acid strength increases and the transparency to high energyradiation of 200 nm or less or electron beam is improved. Thefluorination ratio of the chain-like alkyl group is preferably from 70to 100%, more preferably from 90 to 100%, and it is particularlydesirable that the chain-like alkyl group be a perfluoroalkyl group inwhich all hydrogen atoms are substituted with fluorine atoms.

In formula (b-2), V¹⁰² and V¹⁰³ each independently represents a singlebond, an alkylene group or a fluorinated alkylene group, and is the samegroups as those defined above for V¹⁰¹ in the aforementioned formula(b-1).

In the formula (b-2), L¹⁰¹ and L¹⁰² each independently represents asingle bond or an oxygen atom.

Anion Moiety of Component (b-3)

In formula (b-3), R¹⁰⁶ to R¹⁰⁸ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and is the same groups as those defined above for R¹⁰¹ inthe aforementioned formula (b-1).

L¹⁰³ to L¹⁰⁵ each independently represents a single bond, —CO— or —SO₂—.

{Cation Moiety}

In the formulae (b-1), (b-2) and (b-3), as M′^(m+), a sulfonium cationor an iodonium cation is preferable, and cation moieties represented bygeneral formulae (ca-1) to (ca-4) shown below are particularlypreferable.

In the formulae, each of R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent or an alkenyl group which may have asubstituent; R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² may bemutually bonded to form a ring with the sulfur atom; R²⁰⁸ and R²⁰⁹ eachrepresents a hydrogen atom or an alkyl group of 1 to 5 carbon atoms;R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent or an —SO₂— containing cyclic group which may have asubstituent; L²⁰¹ represents —C(═O)— or —C(═O)—O—; Y²⁰¹ eachindependently represents an arylene group, an alkylene group or analkenylene group; x represents 1 or 2; and W²⁰¹ represents a linkinggroup having a valency of (x+1).

As the aryl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹², an unsubstituted arylgroup of 6 to 20 carbon atoms can be mentioned, and a phenyl group or anaphthyl group is preferable.

As the alkyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹², a chain-like orcyclic alkyl group of 1 to 30 carbon atoms is preferable.

The alkenyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² preferably has 2 to 10carbon atoms.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷, R²¹⁰ and R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,an arylthio group and groups represented by formulae (ca-r-1) to(ca-r-7) shown below.

As the aryl group within the arylthio group as a substituent, the samearyl groups as those described above for R¹⁰¹ can be mentioned, andspecific examples of the arylthio group include a pheylthio group or abiphenylthio group.

In the formulae, R′²⁰¹ each independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent.

As the cyclic group which may have a substituent, the chain-like alkylgroup which may have a substituent and the chain-like alkenyl groupwhich may have a substituent for R′²⁰¹, the same groups as thosedescribed above for R¹⁰¹ in the aforementioned formula (b-1) can bementioned. As the cyclic group which may have a substituent andchain-like alkyl group which may have a substituent, the same groups asthose described above for the acid dissociable group represented by theaforementioned formula (a1-r-2) can be also mentioned.

When R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² are mutually bondedto form a ring with the sulfur atom, these groups may be mutually bondedvia a hetero atom such as a sulfur atom, an oxygen atom or a nitrogenatom, or a functional group such as a carbonyl group, —SO—, —SO₂—,—SO₃—, —COO—, —CONH— or —N(R_(N))— (wherein R_(N) represents an alkylgroup of 1 to 5 carbon atoms). As the ring to be formed, the ringcontaining the sulfur atom in the skeleton thereof is preferably a 3 to10-membered ring, and particularly preferably a 5 to 7-membered ring.Examples of the formed ring include a thiophene ring, a thiazole ring, abenzothiophene ring, a thianthrene ring, a dibenzothiophene ring, a9H-thioxanthene ring, a thioxanthone ring, a phenoxathiin ring, atetrahydrothiophenium ring and a tetrahydrothiopyranium ring.

R²⁰⁸ and R²⁰⁹ each independently represents a hydrogen atom or an alkylgroup of 1 to 5 carbon atoms, is preferably a hydrogen atom or an alkylgroup of 1 to 3 carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents analkyl group, R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent or an —SO₂-containing cyclic group which may have asubstituent.

As the aryl group for R²¹⁰, an unsubstituted aryl group of 6 to 20carbon atoms can be mentioned, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for R²¹⁰, a chain-like or cyclic alkyl group of 1 to30 carbon atoms is preferable.

The alkenyl group for R²¹⁰ preferably has 2 to 10 carbon atoms.

As the —SO₂— containing cyclic group for R²¹⁰ which may have asubstituent, the same groups as the “—SO₂— containing cyclic group” forRa²¹ in the general formula (a2-1) can be mentioned, and the grouprepresented by the aforementioned general formula (a5-r-1) ispreferable.

Y²⁰¹ each independently represents an arylene group, an alkylene groupor an alkenylene group.

As the arylene group for Y²⁰¹, a group in which one hydrogen atom hasbeen removed from an aryl group exemplified as an aromatic hydrocarbongroup for R¹⁰¹ in the aforementioned formula (b-1) can be mentioned.

As the alkylene group and the alkenylene group for Y²⁰¹, the samealiphatic hydrocarbon group as those described above for the divalenthydrocarbon group for Va¹ in the aforementioned general formula (a1-1)can be mentioned.

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), that is, adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupswhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon group as those described above for Ya²¹ in the generalformula (a2-1) can be mentioned. The divalent linking group for W²⁰¹ maybe linear, branched or cyclic, and cyclic is more preferable. Amongthese, an arylene group having two carbonyl groups, each bonded to theterminal thereof is preferable. As the arylene group, a phenylene groupand a naphthylene group can be mentioned. Of these, a phenylene group isparticularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group forW²⁰¹, and a group in which the divalent linking group has been bonded toan another divalent linking group can be mentioned. The trivalentlinking group for W²⁰¹ is preferably an arylene group having twocarbonyl groups bonded thereto.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by formulae (ca-1-1) to (ca-1-63) shownbelow.

In the formulae, g1, g2 and g3 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting the R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by the formula(ca-3) include cations represented by formulae (ca-3-1) to (ca-3-6)shown below.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulae (ca-4-1) to (ca-4-2) shownbelow.

As the component (B2), one type of these acid generators may be usedalone, or two or more types may be used in combination.

When the resist composition of the present invention contains thecomponent (B2), the amount of the component (B2) relative to 100 partsby weight of the component (A) is preferably within a range from 0.5 to60 parts by weight, more preferably from 1 to 50 parts by weight, andstill more preferably from 1 to 40 parts by weight. When the amount ofthe component (B2) is within the above-mentioned range, formation of aresist pattern can be satisfactorily performed. Further, by virtue ofthe above-mentioned range, when each of the components are dissolved inan organic solvent, a uniform solution can be obtained and the storagestability becomes satisfactory.

In the resist composition of the present invention, the amount of thecomponent (B1) based on the entire component (B) is preferably 50% byweight or more, and more preferably 80 to 100% by weight, in terms ofimproving the effect of the present invention.

<Acid Diffusion Control Agent Component; Component (D)>

Moreover, the resist composition of the present invention may include anacid diffusion control agent component (hereafter, frequently referredto as “component (D)”), in addition to the component (A), or in additionto the component (A) and the component (B).

The component (D) functions as an acid diffusion control agent, i.e., aquencher which traps the acid generated from the component (B) and thelike upon exposure.

In the present invention, the component (D) may be a photodecomposablebase (D1) (hereafter, referred to as “component (D1)”) which isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion, or a nitrogen-containing organic compound (D2)(hereafter, referred to as “component (D2)”) which does not fall underthe definition of component (D1).

[Component (D1)]

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions is improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions, the components (d1-1) to (d1-3) are decomposed andthen lose the ability of controlling of acid diffusion (i.e., basicity),and therefore the components (d1-1) to (d1-3) cannot function as aquencher, whereas at unexposed portions, the components (d1-1) to (d1-3)function as a quencher.

In the formulae, Rd¹ to Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent; provided that, inthe formula (d1-2), the carbon atom within the Rd² adjacent to thesulfur atom has no fluorine atom bonded thereto; Yd′ represents a singlebond or a divalent linking group; and M^(m+) each independentlyrepresents a cation having a valency of m.

{Component (d1-1)}

Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹.

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like hydrocarbon group which may have asubstituent are preferable. As the substituents which these groups mayhave, a hydroxy group, a fluorine atom or a fluorinated alkyl group ispreferable.

The aromatic hydrocarbon group is preferably a phenyl group or anaphthyl group.

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

As the chain-like hydrocarbon group, a chain-like alkyl group ispreferable. The chain-like alkyl group preferably has 1 to 10 carbonatoms, and specific examples thereof include a linear alkyl group suchas a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl ora decyl group, and a branched alkyl group such as a 1-methylethyl group,a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

When the chain-like alkyl group is a fluorinated alkyl group containinga fluorine atom or a fluorinated alkyl group as a substituent, thefluorinated alkyl group preferably has 1 to 11 carbon atoms, morepreferably 1 to 8, and still more preferably 1 to 4. The fluorinatedalkyl group may contain an atom other than fluorine. Examples of theatom other than fluorine include an oxygen atom, a carbon atom, ahydrogen atom, a sulfur atom and a nitrogen atom.

As for Rd¹, a fluorinated alkyl group in which part or all of thehydrogen atoms constituting a linear alkyl group have been substitutedwith fluorine atom(s) is preferable, and a fluorinated alkyl group inwhich all of the hydrogen atoms constituting a linear alkyl group havebeen substituted with fluorine atoms (i.e., a linear perfluoroalkylgroup) is more preferable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

Cation Moiety

In formula (d1-1), M^(m+) represents an organic cation having a valencyof m.

The organic cation for M^(m+) is not particularly limited, and examplesthereof include the same cation moieties as those represented by theaforementioned formulae (ca-1) to (ca-4), and cation moietiesrepresented by the aforementioned formulae (ca-1-1) to (ca-1-63) arepreferable.

As the component (d1-1), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-2)}

Anion Moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹, provided that, the carbon atomwithin Rd² group adjacent to the sulfur atom has no fluorine atom bondedthereto (i.e., the carbon atom within Rd² group adjacent to the sulfuratom is not substituted with a fluorine atom). As a result, the anion ofthe component (d1-2) becomes an appropriately weak acid anion, therebyimproving the quenching ability of the component (D).

As Rd², an aliphatic cyclic group which may have a substituent ispreferable, and a group in which one or more hydrogen atoms have beenremoved from adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane (which may have a substituent); or a group in whichone or more hydrogen atoms have been removed from camphor is morepreferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphatichydrocarbon group) for Rd¹ in the formula (d1-1) can be mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

Cation Moiety

In formula (d1-2), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-3)}

Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹, and a cyclic group containing afluorine atom, a chain-like alkyl group or a chain-like alkenyl group ispreferable. Among these, a fluorinated alkyl group is preferable, andmore preferably the same fluorinated alkyl groups as those describedabove for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹.

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

The alkoxy group for Rd⁴ is preferably an alkoxy group of 1 to 5 carbonatoms, and specific examples thereof include a methoxy group, an ethoxygroup, an n-propoxy group, an iso-propoxy group, an n-butoxy group and atert-butoxy group. Among these, a methoxy group and an ethoxy group aredesirable.

As the alkenyl group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned, and a vinyl group, a propenyl group (an allylgroup), a 1-methylpropenyl group and a 2-methylpropenyl group arepreferable. These groups may have an alkyl group of 1 to 5 carbon atomsor a halogenated alkyl group of 1 to 5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned. Among these, as the cyclic group, analicyclic group (e.g., a group in which one or more hydrogen atoms havebeen removed from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane) or an aromatic group (e.g., a phenyl group or anaphthyl group) is preferable. When Rd⁴ is an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithography properties. Alternatively,when Rd⁴ is an aromatic group, the resist composition exhibits anexcellent photoadsorption efficiency in a lithography process using EUVor the like as the exposure source, thereby resulting in the improvementof the sensitivity and the lithography properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup. The divalent linking group for Yd¹ is not particularly limited,and examples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Assuch groups, the same divalent linking groups as those described abovefor Ya²¹ in the formula (a2-1) can be mentioned.

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these groups is preferable. As the alkylenegroup, a linear or branched alkylene group is more preferable, and amethylene group or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

Cation Moiety

In formula (d1-3), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3) can be used, or at least two types of the aforementionedcomponents (d1-1) to (d1-3) can be used in combination.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 10 parts byweight, more preferably from 0.5 to 8 parts by weight, and still morepreferably from 1 to 8 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithography properties andexcellent resist pattern shape can be obtained. On the other hand, whenthe amount of the component (D1) is no more than the upper limit of theabove-mentioned range, sensitivity can be maintained at a satisfactorylevel, and through-put becomes excellent.

The production methods of the components (d1-1) and (d1-2) are notparticularly limited, and the components (d1-1) and (d1-2) can beproduced by conventional methods.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 10.0 parts byweight, more preferably from 0.5 to 8.0 parts by weight, and still morepreferably from 1.0 to 8.0 parts by weight. When the amount is at leastas large as the lower limit of the above-mentioned range, excellentlithography properties and excellent resist pattern shape can beobtained. On the other hand, when the amount is no more than the upperlimit of the above-mentioned range, sensitivity can be maintained at asatisfactory level, and through-put becomes excellent.

(Component (D2))

The component (D) may contain a nitrogen-containing organic compound(D2) (hereafter, referred to as component (D2)) which does not fallunder the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine, particularly a secondary aliphatic amine or tertiaryaliphatic amine is preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkyl amines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanol amine triacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include aniline, pyridine,4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole andderivatives thereof, as well as diphenylamine, triphenylamine,tribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one type of compound may be used alone, or two ormore types may be used in combination.

The component (D2) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A). When the amount of the component (D2) is within theabove-mentioned range, the shape of the resist pattern and the postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer are improved.

As the component (D), one type of compound may be used, or two or moretypes of compounds may be used in combination.

When the resist composition of the present invention contains thecomponent (D), the amount of the component (D) relative to 100 parts byweight of the component (A) is preferably within a range from 0.1 to 15parts by weight, more preferably from 0.3 to 12 parts by weight, andstill more preferably from 0.5 to 12 parts by weight. When the amount ofthe component (D) is at least as large as the lower limit of theabove-mentioned range, various lithography properties (such as LWR) ofthe resist composition are improved. Further, a resist pattern having anexcellent shape can be obtained. On the other hand, when the amount isno more than the upper limit of the above-mentioned range, sensitivitycan be maintained at a satisfactory level, and through-put becomesexcellent.

<Optional Components>

[Component (E)]

Furthermore, in the resist composition of the present invention, forpreventing any deterioration in sensitivity, and improving the resistpattern shape and the post exposure stability of the latent image formedby the pattern-wise exposure of the resist layer, at least one compound(E) (hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof can be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of phosphorous oxo acid derivatives include esters in which ahydrogen atom within the above-mentioned phosphorous oxo acids issubstituted with a hydrocarbon group. Examples of the hydrocarbon groupinclude an alkyl group of 1 to 5 carbon atoms and an aryl group of 6 to15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phenylphosphinic acidand phosphinic acid esters.

As the component (E), one type may be used alone, or two or more typesmay be used in combination.

The component (E) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A).

[Component (F)]

In the present invention, the resist composition may further include afluorine additive (hereafter, referred to as “component (F)”) forimparting water repellency to the resist film.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of astructural unit (f1) represented by formula (f1-1) shown below and theaforementioned structural unit (a1); and a copolymer of a structuralunit (f1) represented by the formula (f1-1) shown below, a structuralunit derived from acrylic acid or methacrylic acid and theaforementioned structural unit (a1) are preferable. As the structuralunit (a1) to be copolymerized with a structural unit (f1) represented byformula (f1-1) shown below, a structural unit derived from1-ethyl-1-cyclooctyl(meth)acrylate or a structural unit represented bythe aforementioned formula (a1-2-01) is preferable.

In the formula, R is the same as defined above; Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 1 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R is the same as defined above. As R, a hydrogen atomor a methyl group is preferable.

In formula (f1-1), examples of the halogen atom for Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable. Examples of thealkyl group of 1 to 5 carbon atoms for Rf¹⁰² and Rf¹⁰³ include the samealkyl group of 1 to 5 carbon atoms as those described above for R, and amethyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group of 1 to 5 carbon atoms represented by Rf¹⁰² andRf¹⁰³ include groups in which part or all of the hydrogen atoms of theaforementioned alkyl groups of 1 to 5 carbon atoms have been substitutedwith halogen atoms. Examples of the halogen atom include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is particularly desirable. Among these, as Rf¹⁰² and Rf¹⁰³, ahydrogen atom, a fluorine atom or an alkyl group of 1 to 5 carbon atomsis preferable, and a hydrogen atom, a fluorine atom, a methyl group oran ethyl group is more preferable.

In formula (f1-1), nf¹ represents an integer of 1 to 5, preferably aninteger of 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 5 carbonatoms is preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃ and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ aremost preferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight isno more than the upper limit of the above-mentioned range, the resistcomposition exhibits a satisfactory solubility in a resist solvent. Onthe other hand, when the weight average molecular weight is at least aslarge as the lower limit of the above-mentioned range, dry etchingresistance and the cross-sectional shape of the resist pattern becomessatisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

As the component (F), one type may be used alone, or two or more typesmay be used in combination.

The component (F) is typically used in an amount within a range from 0.5to 10 parts by weight, relative to 100 parts by weight of the component(A).

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

[Component (S)]

The resist composition of the present invention can be prepared bydissolving the materials for the resist composition in an organicsolvent (hereafter, frequently referred to as “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a uniform solution, and one or more kindsof any organic solvent can be appropriately selected from those whichhave been conventionally known as solvents for a chemically amplifiedresist.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone (MEK), cyclohexanone, methyl-n-pentylketone (2-heptanone), and methyl isopentyl ketone; polyhydric alcohols,such as ethylene glycol, diethylene glycol, propylene glycol anddipropylene glycol; compounds having an ester bond, such as ethyleneglycol monoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

These solvents can be used individually, or in combination as a mixedsolvent.

Among these, PGMEA, PGME, γ-butyrolactone and EL are preferable.

Further, among the mixed solvents, a mixed solvent obtained by mixingPGMEA with a polar solvent is preferable. The mixing ratio (weightratio) of the mixed solvent can be appropriately determined, taking intoconsideration the compatibility of the PGMEA with the polar solvent, butis preferably in the range of 1:9 to 9:1, more preferably from 2:8 to8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL weight ratio or PGMEA:cyclohexanone weight ratio ispreferably from 1:9 to 9:1, and more preferably from 2:8 to 8:2.Alternatively, when PGME is mixed as the polar solvent, the PGMEA:PGMEis preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2, andstill more preferably 3:7 to 7:3.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of aresist solution to a substrate. In general, the organic solvent is usedin an amount such that the solid content of the resist compositionbecomes within the range from 1 to 20% by weight, and preferably from 2to 15% by weight.

The resist compositions of the present invention exhibited excellentlithography properties such as sensitivity and LWR. The reason for thishas not been elucidated yet, but is presumed as follows.

The structural unit (a0) in the polymeric compound (A1) contained in theresist composition of the present invention increases the compatibilitywith a developing solution, and therefore, improvement in sensitivityand LWR can be expected.

The acid generator component contained in the resist composition of thepresent invention has an anion group which has a relatively bulkyfunctional group, and therefore, the diffusion length of the acidgenerator is shortened. By using the polymeric compound containing thestructural unit (a0) and the acid generated are used in combination(that is, by using the polymeric compound exhibiting excellentsensitivity and the acid generator having a short diffusion length incombination), sensitivity can be appropriately controlled, andlithography properties such as sensitivity and LWR can be improved.

The structural unit (a0) in the polymeric compound contained in theresist composition of the present invention has a hydrophilic group, andhence, it is presumed that the interaction with acid can be improved.

<<Method of Forming a Resist Pattern>>

The method of forming a resist pattern of the second aspect of thepresent invention includes: forming a resist film on a substrate using aresist composition of the present invention; conducting exposure of theresist film; and developing the resist film to form a resist pattern.

The method for forming a resist pattern according to the presentinvention can be performed, for example, as follows.

Firstly, a resist composition of the present invention is applied to asubstrate using a spinner or the like, and a bake treatment (postapplied bake (PAB)) is conducted at a temperature of 80 to 150° C. for40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such as an ArF exposureapparatus, an electron beam lithography apparatus or an EUV exposureapparatus, or by patterning via direct irradiation with an electron beamwithout using a mask pattern, baking treatment (post exposure baking(PEB)) is conducted under temperature conditions of 80 to 150° C. for 40to 120 seconds, and preferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment.

The developing treatment is conducted using an alkali developingsolution in the case of an alkali developing process, and a developingsolution containing an organic solvent (organic developing solution) inthe case of a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing. In this manner, a resist pattern can beobtained.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic anti-reflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm is formed (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiations such as ArF excimerlaser, KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays(EUV), vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, andsoft X-rays. The resist composition of the present invention iseffective to KrF excimer laser, ArF excimer laser, EB and EUV.

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long as it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H₅ or C₅H₃F₇ as the main component, which preferably have aboiling point within a range from 70 to 180° C. and more preferably from80 to 160° C. A fluorine-based inert liquid having a boiling pointwithin the above-mentioned range is advantageous in that the removal ofthe immersion medium after the exposure can be conducted by a simplemethod.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, amide solvents and ether solvents, and hydrocarbon solvents.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

EXAMPLES

As follows is a description of examples of the present invention,although the scope of the present invention is by no way limited bythese examples.

<<Preparation of Resist Composition 1>>

The components were mixed in the mixing ratio indicated in followingTables 1 to 6 to obtain resist compositions (Examples 1 to 42,Comparative Examples 1 to 14).

TABLE 1 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Comparative (A)-1 (B)-1 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 Example 1 [100] [13.9] [5.15] [4.0] [0.2] [100][4000] Comparative (A)-1 (B)-2 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 2[100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Comparative (A)-1 (B)-3(D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 3 [100] [15.1] [5.15] [4.0] [0.2][100] [4000] Comparative (A)-1 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2Example 4 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Comparative (A)-1(B)-5 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 5 [100] [15.2] [5.15] [4.0][0.2] [100] [4000] Comparative (A)-1 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2Example 6 [100] [14.8] [5.15] [4.0] [0.2] [100] [4000] Comparative (A)-1(B)-7 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 7 [100] [14.9] [5.15] [4.0][0.2] [100] [4000] Comparative (A)-1 (B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2Example 8 [100] [19.9] [5.15] [4.0] [0.2] [100] [4000] Comparative (A)-2(B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 9 [100] [13.9] [5.15] [4.0][0.2] [100] [4000] Comparative (A)-3 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2Example 10 [100] [13.9] [5.15] [4.0] [0.2] [100] [4000] Comparative(A)-4 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 11 [100] [13.9] [5.15][4.0] [0.2] [100] [4000] Comparative (A)-5 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 Example 12 [100] [13.9] [5.15] [4.0] [0.2] [100] [4000]Comparative (A)-6 (B)-1 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 Example 13 [100][13.9] [5.15] [4.0] [0.2] [100] [4000] Comparative (A)-7 (B)-1 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 Example 14 [100] [13.9] [5.15] [4.0] [0.2] [100][4000]

TABLE 2 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 1 (A)-2 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000]Example 2 (A)-2 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15][4.0] [0.2] [100] [4000] Example 3 (A)-2 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 4 (A)-2 (B)-5(D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2] [100][4000] Example 5 (A)-2 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [14.8][5.15] [4.0] [0.2] [100] [4000] Example 6 (A)-2 (B)-7 (D)-1 (F)-1 (E)-1(S)-1 (S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000] Example 7 (A)-2(B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15] [4.0] [0.2][100] [4000]

TABLE 3 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 8 (A)-3 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000]Example 9 (A)-3 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15][4.0] [0.2] [100] [4000] Example 10 (A)-3 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 11 (A)-3(B)-5 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2][100] [4000] Example 12 (A)-3 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100][14.8] [5.15] [4.0] [0.2] [100] [4000] Example 13 (A)-3 (B)-7 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000]Example 14 (A)-3 (B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15][4.0] [0.2] [100] [4000]

TABLE 4 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 15 (A)-4 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000]Example 16 (A)-4 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15][4.0] [0.2] [100] [4000] Example 17 (A)-4 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 18 (A)-4(B)-5 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2][100] [4000] Example 19 (A)-4 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100][14.8] [5.15] [4.0] [0.2] [100] [4000] Example 20 (A)-4 (B)-7 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000]Example 21 (A)-4 (B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15][4.0] [0.2] [100] [4000]

TABLE 5 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 22 (A)-5 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000]Example 23 (A)-5 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15][4.0] [0.2] [100] [4000] Example 24 (A)-5 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 25 (A)-5(B)-5 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2][100] [4000] Example 26 (A)-5 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100][14.8] [5.15] [4.0] [0.2] [100] [4000] Example 27 (A)-5 (B)-7 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000]Example 28 (A)-5 (B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15][4.0] [0.2] [100] [4000]

TABLE 6 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 29 (A)-6 (B)-2 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000]Example 30 (A)-6 (B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15][4.0] [0.2] [100] [4000] Example 31 (A)-6 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 32 (A)-6(B)-5 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2][100] [4000] Example 33 (A)-6 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100][14.8] [5.15] [4.0] [0.2] [100] [4000] Example 34 (A)-6 (B)-7 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000]Example 35 (A)-6 (B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15][4.0] [0.2] [100] [4000] Example 36 (A)-7 (B)-2 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.5] [5.15] [4.0] [0.2] [100] [4000] Example 37 (A)-7(B)-3 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [15.1] [5.15] [4.0] [0.2][100] [4000] Example 38 (A)-7 (B)-4 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100][14.5] [5.15] [4.0] [0.2] [100] [4000] Example 39 (A)-7 (B)-5 (D)-1(F)-1 (E)-1 (S)-1 (S)-2 [100] [15.2] [5.15] [4.0] [0.2] [100] [4000]Example 40 (A)-7 (B)-6 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [14.8] [5.15][4.0] [0.2] [100] [4000] Example 41 (A)-7 (B)-7 (D)-1 (F)-1 (E)-1 (S)-1(S)-2 [100] [14.9] [5.15] [4.0] [0.2] [100] [4000] Example 42 (A)-7(B)-8 (D)-1 (F)-1 (E)-1 (S)-1 (S)-2 [100] [19.9] [5.15] [4.0] [0.2][100] [4000]

-   -   (A)-1 to (A)-7: polymeric compounds (A)-1 to (A)-7 shown below    -   (B)-1 to (B)-8: compounds (B)-1 to (B)-8 shown below    -   (D)-1: compound (D)-1 shown below    -   (F)-1: polymeric compound (F)-1 shown below (molar ratio:        1/m=77/23), Mw: 23,100, Mw/Mn: 1.78    -   (E)-1: salicylic acid    -   (S)-1: γ-butyrolactone    -   (S)-2: a mixed solvent of PGMEA/PGME/cyclohexanone=45/30/25        (weight ratio)

Formation of Resist Pattern Examples 1 to 42, Comparative Examples 1 to14

An organic anti-reflection film composition (product name: ARC95,manufactured by Brewer Science Ltd.) was applied to an 12-inch siliconwafer using a spinner, and the composition was then baked at 205° C. for60 seconds on a hotplate and dried, thereby forming an organicanti-reflection film having a film thickness of 90 nm.

Then, each of the above resist composition indicated in Table 1(Examples 1 to 42, Comparative Examples 1 to 14) was applied to theorganic antireflection film using a spinner, and was then prebaked (PAB)on a hotplate at 110° C. for 60 seconds and dried, thereby forming aresist film having a film thickness of 90 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a mask, using an immersion lithographyArF exposure apparatus NSR-S609B (manufactured by Nikon Corporation; NA(numerical aperture)=1.07; Dipole (in/out=0.78/0.97) with Polano;immersion medium: water).

Further, PEB treatment was conducted at 95° C. for 60 seconds.

Next, an alkali development was conducted for 10 seconds at 23° C. in a2.38% by weight aqueous solution of tetramethylammonium hydroxide (TMAH)(product name: NMD-3; manufactured by Tokyo Ohka Kogyo Co., Ltd.). Then,the resist was washed for 30 seconds with pure water, followed by dryingby shaking. After development, a post bake was conducted at 100° C. for45 seconds.

As a result, in each of the examples, a 1:1 line and space pattern (LSpattern) having a line width of 50 nm and a pitch of 100 nm was formed.

[Evaluation of Optimum Exposure Dose (Eop)]

In the above “formation of resist pattern”, the optimum exposure doseEop (μC/cm²) with which the LS pattern having the target size could beformed was determined. The results are indicated under “Eop” in Tables 7to 12.

[Evaluation of Mask Error Factor (MEEF)]

In the same manner as in the formation of LS pattern, with the sameexposure dose, LS patterns with a pitch of 98 nm were formed using amask pattern targeting a line pattern size of 45 to 54 nm (10 targetsizes at intervals of 1 nm). The value of the mask error factor (MEEF)was determined as the gradient of a graph obtained by plotting thetarget size (nm) on the horizontal axis, and the size (nm) of the formedline patterns on the vertical axis. A MEEF value (gradient of theplotted line) closer to 1 indicates that a resist pattern faithful tothe mask pattern was formed.

The results are shown in Tables 7 to 12.

[Evaluation of Line Width Roughness (LWR)]

With respect to each of the LS patterns, the space width at 400 pointsin the lengthwise direction of the space was measured using a measuringscanning electron microscope (SEM) (product name: S-9380, manufacturedby Hitachi High-Technologies Corporation; acceleration voltage: 300V).From the results, the value of 3 times the standard deviation s (i.e., 3s) was determined, and the average of the 3 s values at 400 points wascalculated as a yardstick of LWR. The results are shown in Tables 7 to12.

The smaller this 3 s value is, the lower the level of roughness of theline width, indicating that a LS pattern with a uniform width wasobtained.

TABLE 7 LWR Eop (nm) MEEF Comparative 22.3 4.46 2.12 Example 1Comparative 25.3 2.72 1.51 Example 2 Comparative 28.0 2.69 1.32 Example3 Comparative 23.8 2.68 1.49 Example 4 Comparative 24.1 2.56 1.45Example 5 Comparative 25.3 2.54 1.49 Example 6 Comparative 25.6 2.511.45 Example 7 Comparative 33.0 2.68 1.45 Example 8 Comparative 18.14.41 2.14 Example 9 Comparative 20.3 4.12 2.12 Example 10 Comparative29.0 4.12 2.12 Example 11 Comparative 29.0 4.19 2.15 Example 12Comparative 20.3 3.98 2.34 Example 13 Comparative 19.0 4.00 2.35 Example14

TABLE 8 LWR Eop (nm) MEEF Example 1 20.5 2.69 1.52 Example 2 22.7 2.521.29 Example 3 19.1 2.61 1.41 Example 4 19.6 2.49 1.42 Example 5 20.52.38 1.39 Example 6 20.5 2.32 1.38 Example 7 26.8 2.42 1.41

TABLE 9 LWR Eop (nm) MEEF Example 8 23.5 2.71 1.51 Example 9 25.8 2.591.95 Example 10 22.4 2.65 1.35 Example 11 22.7 2.56 1.38 Example 12 23.02.47 1.31 Example 13 23.6 2.39 1.35 Example 14 30.7 2.42 1.49

TABLE 10 LWR Eop (nm) MEEF Example 15 32.9 2.68 1.51 Example 16 36.42.42 1.99 Example 17 30.9 2.32 1.35 Example 18 31.3 2.23 1.38 Example 1932.9 2.31 1.31 Example 20 33.3 2.45 1.35 Example 21 4.29 2.34 1.21

TABLE 11 LWR Eop (nm) MEEF Example 22 32.9 2.68 1.49 Example 23 36.42.42 2.01 Example 24 30.9 2.32 1.34 Example 25 31.3 2.23 1.23 Example 2632.9 2.31 1.32 Example 27 33.3 2.48 1.42 Example 28 42.9 2.34 1.29

TABLE 12 LWR Eop (nm) MEEF Example 29 23.3 2.72 1.59 Example 30 25.82.57 1.98 Example 31 22.6 2.59 1.41 Example 32 21.9 2.43 1.32 Example 3323.3 2.48 1.43 Example 34 23.0 2.43 1.45 Example 35 28.7 2.29 1.34Example 36 21.2 2.7 1.55 Example 37 23.4 2.55 1.80 Example 38 20.5 2.61.45 Example 39 20.1 2.5 1.31 Example 40 22.1 2.5 1.43 Example 41 22.02.4 1.45 Example 42 25.0 2.3 1.32

From the results shown above, it was confirmed that, a comparison wasmade between Examples and Comparative Examples in which the samecomponent (B) was used, Examples exhibited excellent LWR as compared toComparative Examples.

It was confirmed that, when the ester bond for L¹¹ in general formula(b1) was arranged to form V¹¹—C(═O)O—Y¹¹, MEEF exhibited an excellentvalue, and in particular, when a cyclic group for R¹¹ had a substituent,LWR was especially good.

<<Preparation of Resist Composition 2>>

The components were mixed in the mixing ratio indicated in followingTable 13 to obtain resist compositions (Examples 43 to 49, ComparativeExample 16).

TABLE 13 Component Component Component Component Component ComponentComponent (A) (B) (D) (F) (E) (S)-1 (S)-2 Example 43 (A)-8 (B)-2 (D)-2(F)-1 (E)-1 (S)-1 (S)-2 [100] [11.8] [4.95] [4.0] [0.2] [100] [4000]Example 44 (A)-8 (B)-3 (D)-2 (F)-1 (E)-1 (S)-1 (S)-2 [100] [12.3] [4.95][4.0] [0.2] [100] [4000] Example 45 (A)-8 (B)-4 (D)-2 (F)-1 (E)-1 (S)-1(S)-2 [100] [11.8] [4.95] [4.0] [0.2] [100] [4000] Example 46 (A)-8(B)-5 (D)-2 (F)-1 (E)-1 (S)-1 (S)-2 [100] [12.4] [4.95] [4.0] [0.2][100] [4000] Example 47 (A)-8 (B)-6 (D)-2 (F)-1 (E)-1 (S)-1 (S)-2 [100][12.1] [4.95] [4.0] [0.2] [100] [4000] Example 48 (A)-8 (B)-7 (D)-2(F)-1 (E)-1 (S)-1 (S)-2 [100] [12.1] [4.95] [4.0] [0.2] [100] [4000]Example 49 (A)-8 (B)-8 (D)-2 (F)-1 (E)-1 (S)-1 (S)-2 [100] [16.2] [4.95][4.0] [0.2] [100] [4000] Comparative (A)-8 (B)-1 (D)-2 (F)-1 (E)-1 (S)-1(S)-2 Example 16 [100] [11.3] [4.95] [4.0] [0.2] [100] [4000]

In the table, the reference characters indicate the following. Further,the values in brackets [ ] indicate the amount (in terms of parts byweight) of the component added.

-   -   (A)-8: polymeric compound (A)-8 shown below    -   (B)-1 to (B)-8: the aforementioned compounds (B)-1 to (B)-8    -   (D)-2: compound (D)-2 shown below    -   (F)-1: the aforementioned polymeric compound (F)-1 (molar ratio:        1/m=77/23), Mw: 23,100, Mw/Mn: 1.78    -   (E)-1: salicylic acid    -   (S)-1: γ-butyrolactone    -   (S)-2: a mixed solvent of PGMEA/PGME/cyclohexanone=45/30/25        (weight ratio)

Formation of Resist Pattern 2 Negative-Tone Solvent Developing Examples43 to 49 Comparative Example 16

An organic anti-reflection film composition (product name: ARC29,manufactured by Brewer Science Ltd.) was applied to an 12-inch siliconwafer using a spinner, and the composition was then baked at 205° C. for60 seconds on a hotplate and dried, thereby forming an organicanti-reflection film having a film thickness of 82 nm.

Then, the above resist composition was applied to the organicantireflection film using a spinner, and was then prebaked (PAB) on ahotplate at 110° C. for 50 seconds and dried, thereby forming a resistfilm having a film thickness of 85 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a mask pattern, using an exposureapparatus NSR-5609B (manufactured by Nikon Corporation; NA (numericalaperture)=1.07; Dipole 0.97/0.78 with Polano). Further, a post exposurebake (PEB) treatment was conducted at 90° C. for 50 seconds.

Next, a solvent development was conducted for 31 seconds at 23° C. usingbutyl acetate, followed by drying by shaking.

As a result, in each of the examples, a line and space pattern wasformed. In each of the examples, a line and space pattern having a spacewidth of 47 nm and a pitch of 110 nm was formed.

With respect to the pattern formed in the aforementioned <Formation ofresist pattern 2>, [Evaluation of optimum exposure dose (Eop)],[Evaluation of line width roughness (LWR)] and [Evaluation of mask errorfactor (MEEF)] were conducted in the same manner as described above.

Further, the following [Evaluation of exposure latitude (EL margin)] and[Measurement of pattern height] were also conducted. The results areshown in Table 14.

[Evaluation of Exposure Latitude (EL Margin)]

With respect to the exposure dose for formation of the LS pattern, theexposure dose with which the LS pattern having a dimension of the targetdimension ±5% was formed was determined, and the EL margin (unit: %) wasdetermined by the following formula.

EL margin (%)=(|E1−E2|/Eop)×100

E1: the exposure dose (mJ/cm²) for forming an LS pattern with a spacewidth of 44.7 nm

E2: the exposure dose (mJ/cm²) for forming an LS pattern having a spacewidth of 49.4 nm

The larger the exposure margin, the smaller the variation in the patternsize depending on the change in the exposure dose, thereby resulting infavorable improvement in the process margin.

[Measurement of Pattern Height]

The pattern height of the LS pattern formed in the aforementioned<Formation of resist pattern 2> was measured using a wafershape/characteristic measurement apparatus (product name: SCD-XT,manufactured by KLA-TENCOR Corporation).

TABLE 14 Pattern 5% EL Height LWR Eop (%) (nm) (nm) MEEF Example 43 20.87.42 69.5 3.21 3.32 Example 44 21.3 7.52 70.2 2.98 3.24 Example 45 20.17.32 73.2 2.57 2.81 Example 46 20.3 7.52 79.1 2.43 2.34 Example 47 17.27.89 81.2 2.39 2.24 Example 48 20.9 8.92 80.5 2.32 2.14 Example 49 21.59.32 82.5 2.29 2.09 Comparative 22.5 5.29 60.2 4.42 4.21 Example 16

From the results shown above, it was confirmed that, in the patternformed by negative-tone solvent developing, Examples exhibited excellentEop, EL margin, pattern height, LWR and MEEF, as compared to ComparativeExample.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist composition comprising a base component(A) which exhibits changed solubility in a developing solution underaction of acid and an acid generator component (B) which generates acidupon exposure, the base component (A) comprising a polymeric compound(A1) comprising a structural unit (a0) represented by general formula(a0-1) shown below, and the acid generator component (B) comprising acompound (B1) represented by general formula (b1) shown below:

wherein R represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya¹represents a single bond or a divalent linking group; La¹ and La² eachindependently represents —SO₂— or —C(═O)—; Ra¹ represents a cyclic groupwhich may have a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent;n₁ and n₂ each independently represents 0 or 1, and at least one of n1and n2 is 1, provided that, when La¹ is —SO₂— and n₁ is 1, n₂ is 1, andwhen La² is —SO₂— and n₂ is 1, Ya¹ is a chain-like divalent linkinggroup; R¹¹ represents a cyclic group of 5 to 30 carbon atoms which mayhave a substituent; V¹¹ represents a single bond or an alkylene group of1 to 6 carbon atoms; L¹¹ represents an ester bond; Y¹¹ represents analkylene group of 1 to 5 carbon atoms which may have a fluorine atom; mrepresents an integer of 1 or more; and M^(m+) represents an organiccation having a valency of m.
 2. The resist composition according toclaim 1, wherein the structural unit (a0) is at least one structuralunit represented by any one of general formulae (a0-1-1) to (a0-1-3)shown below:

wherein R represents a hydrogen atom, an alkyl group of 1 to 5 carbonatoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya¹represents a single bond or a divalent linking group; La¹ and La² eachindependently represents —SO₂— or —C(═O)—, provided that, when La² is—SO₂—, Ya¹ represents a chain-like divalent linking group; n₁ represents0 or 1; Ra¹ represents a cyclic group which may have a substituent, achain-like alkyl group which may have a substituent or a chain-likealkenyl group which may have a substituent.
 3. The resist compositionaccording to claim 2, wherein Ya¹ represents an ester bond [—C(═O)—O-],an ether bond (—O—), a linear or branched alkylene group, a combinationof these, or a single bond; Ra¹ is a group selected from the groupconsisting of a lactone-containing cyclic group, an —SO₂— containingcyclic group, a substituted aryl group, a polycyclic monovalentalicyclic hydrocarbon group which may have a substituent, a monovalentheterocycle, and a fluorinated alkyl group.
 4. The resist compositionaccording to claim 2, wherein R¹¹ is an adamantyl group which may have asubstituent, a norbornyl group which may have a substituent or a cyclicgroup containing a steroid skeleton which may have a substituent,provided that, when R¹¹ is an adamantly group or a norbornyl group, R¹¹has 2 or 3 alkyl groups, one hydroxyl group or one oxo group as asubstituent; and when R¹¹ is a polycycloalkane containing a condensedring-type polycyclic skeleton, R¹¹ has 3 to 5 substituents.
 5. Theresist composition according to claim 4, wherein L¹¹ is—C(═O)—O-configured to form —V¹¹—C(═O)—O—Y¹¹—.
 6. The resist compositionaccording to claim 3, wherein R¹¹ is an adamantyl group which may have asubstituent, a norbornyl group which may have a substituent or a cyclicgroup containing a steroid skeleton which may have a substituent,provided that, when R¹¹ is an adamantly group or a norbornyl group, R¹¹has 2 or 3 alkyl groups, one hydroxyl group or one oxo group as asubstituent; and when R^(H) is a polycycloalkane containing a condensedring-type polycyclic skeleton, R¹¹ has 3 to 5 substituents.
 7. Theresist composition according to claim 6, wherein L¹¹ is—C(═O)—O-configured to form —V¹¹—C(═O)—O—Y¹¹—.
 8. The resist compositionaccording to claim 1, wherein the polymeric compound (A1) comprises astructural unit (a1) containing an acid decomposable group that exhibitsincreased polarity by the action of acid.
 9. The resist compositionaccording to claim 1, wherein the polymeric compound (A1) comprises astructural unit (a2) containing a lactone-containing cyclic group.
 10. Amethod of forming a resist pattern, comprising: forming a resist film ona substrate using a resist composition of claim 1; conducting exposureof the resist film; and developing the resist film to form a resistpattern.
 11. A method of forming a resist pattern, comprising: forming aresist film on a substrate using a resist composition of claim 1;conducting exposure of the resist film; and developing the resist filmto form a negative resist pattern with a developing solution containingan organic solvent.
 12. A method of forming a resist pattern,comprising: forming a resist film on a substrate using a resistcomposition of claim 2; conducting exposure of the resist film; anddeveloping the resist film to form a negative resist pattern with adeveloping solution containing an organic solvent.
 13. A method offorming a resist pattern, comprising: forming a resist film on asubstrate using a resist composition of claim 3; conducting exposure ofthe resist film; and developing the resist film to form a negativeresist pattern with a developing solution containing an organic solvent.14. A method of forming a resist pattern, comprising: forming a resistfilm on a substrate using a resist composition of claim 4; conductingexposure of the resist film; and developing the resist film to form anegative resist pattern with a developing solution containing an organicsolvent.
 15. A method of forming a resist pattern, comprising: forming aresist film on a substrate using a resist composition of claim 5;conducting exposure of the resist film; and developing the resist filmto form a negative resist pattern with a developing solution containingan organic solvent.
 16. A method of forming a resist pattern,comprising: forming a resist film on a substrate using a resistcomposition of claim 6; conducting exposure of the resist film; anddeveloping the resist film to form a negative resist pattern with adeveloping solution containing an organic solvent.
 17. A method offorming a resist pattern, comprising: forming a resist film on asubstrate using a resist composition of claim 7; conducting exposure ofthe resist film; and developing the resist film to form a negativeresist pattern with a developing solution containing an organic solvent.18. A method of forming a resist pattern, comprising: forming a resistfilm on a substrate using a resist composition of claim 8; conductingexposure of the resist film; and developing the resist film to form anegative resist pattern with a developing solution containing an organicsolvent.
 19. A method of forming a resist pattern, comprising: forming aresist film on a substrate using a resist composition of claim 9;conducting exposure of the resist film; and developing the resist filmto form a negative resist pattern with a developing solution containingan organic solvent.